VMware uses a mix of percent-, pipe- and base64-encoding in
different combinations in different places.

Add a testcase for this.

QueryVirtualDiskUuid is only available on an ESX(i) server. vCenter
returns an NotImplemented fault and a GSX server is missing the
VirtualDiskManager completely. Therefore only use QueryVirtualDiskUuid
with an ESX(i) server and fall back to path as storage volume key for
vCenter and GSX server.

VirtualDisks are .vmdk file based. Other files in a datastore
like .iso or .flp files don't have a UUID attached, fall back
to the path as key for them.

Instead of splitting the path part of a datastore path into
directory and file name, keep this in one piece. An example:

  "[datastore] directory/file"

was split into this before:

  datastoreName = "datastore"
  directoryName = "directory"
  fileName = "file"

Now it's split into this:

  datastoreName = "datastore"
  directoryName = "directory"
  directoryAndFileName = "directory/file"

This simplifies code using esxUtil_ParseDatastorePath, because
directoryAndFileName is used more often than fileName. Also the
old approach expected the datastore path to reference an actual
file, but this isn't always correct, especially when listing
volumes. In that case esxUtil_ParseDatastorePath is used to parse
a path that references a directory. This fails for a vpx://
connection because the vCenter returns directory paths with a
trailing '/'. The new approach is robust against this and the
actual decision if the datastore path should reference a file or
a directory is up to the caller of esxUtil_ParseDatastorePath.

Update the tests accordingly.

This allows to list existing volumes and to retrieve information
about them.

With the previous storage pool UUID source not all storage pools
had a proper UUID, especially GSX storage pools. The mount path
is unique per host and cannot change during the lifetime of the
datastore. Therefore, it's MD5 sum can be used as UUID.

Use gnulib's crypto/md5 module to generate the MD5 sum.

Now all storage pool types expose the target path.

Don't rely on summary.url anymore, because its value is different
between an esx:// and vpx:// connection. Use host.mountInfo.path
instead.

Don't fallback to lookup by UUID (actually lookup by absolute path)
in esxVI_LookupDatastoreByName when lookup by name fails. Add a
seperate function for this: esxVI_LookupDatastoreByAbsolutePath

Now a vpx:// connection has an explicitly specified host. This
allows to enabled several functions for a vpx:// connection
again, like host UUID, hostname, general node info, max vCPU
count, free memory, migration and defining new domains.

Lookup datacenter, compute resource, resource pool and host
system once and cache them. This simplifies the rest of the
code and reduces overall HTTP(S) traffic a bit.

esx:// and vpx:// can be mixed freely for a migration.

Ensure that migration source and destination refer to the
same vCenter. Also directly encode the resource pool and
host system object IDs into the migration URI in the prepare
function. Then directly build managed object references in
the perform function instead of re-looking up already known
information.

Add a pointer to the primary context of a connection and use it in all
driver functions that don't dependent on the context type. This includes
almost all functions that deal with a virDomianPtr. Therefore, using
a vpx:// connection allows you to perform all the usual domain related
actions like start, destroy, suspend, resume, dumpxml etc.

Some functions that require an explicitly specified ESX server don't work
yet. This includes the host UUID, the hostname, the general node info, the
max vCPU count and the free memory. Also not working yet are migration and
defining new domains.

Eliminate almost all backward jumps by replacing this common pattern:

int
some_random_function(void)
{
    int result = 0;
    ...

  cleanup:
    <unconditional cleanup code>
    return result;

  failure:
    <cleanup code in case of an error>
    result = -1;
    goto cleanup
}

with this simpler pattern:

int
some_random_function(void)
{
    int result = -1;
    ...
    result = 0;

  cleanup:
    if (result < 0) {
        <cleanup code in case of an error>
    }

    <unconditional cleanup code>
    return result;
}

Add a bool success variable in functions that don't have a int result
that can be used for the new pattern.

Also remove some unnecessary memsets in error paths.

Allows listing existing pools and requesting information about them.

Alter the esxVI_ProductVersion enum in a way that allows to check for
product type by masking.

Also define ESX_ERROR and ESX_VI_ERROR in a central place, instead of
defining them in each source file.

Add ESX_ERROR and ESX_VI_ERROR to the msg_gen_function list in cfg.mk.

Update po/POTFILES.in accordingly.

Replace 'method' with 'function' and get the filename's suffix right.

Also add vol wiping to ESX storage driver struct

Prior to this patch, there was an inconsistent mix between GNU and C99.

For consistency, and potential portability to other compilers, stick
with the C99 vararg macro syntax.

* src/conf/cpu_conf.c (virCPUReportError): Use C99 rather than GNU
  vararg macro syntax.
* src/conf/domain_conf.c (virDomainReportError): Likewise.
* src/conf/domain_event.c (eventReportError): Likewise.
* src/conf/interface_conf.c (virInterfaceReportError): Likewise.
* src/conf/network_conf.c (virNetworkReportError): Likewise.
* src/conf/node_device_conf.h (virNodeDeviceReportError): Likewise.
* src/conf/secret_conf.h (virSecretReportError): Likewise.
* src/conf/storage_conf.h (virStorageReportError): Likewise.
* src/esx/esx_device_monitor.c (ESX_ERROR): Use C99 rather than
  GNU vararg macro syntax.
* src/esx/esx_driver.c (ESX_ERROR): Likewise.
* src/esx/esx_interface_driver.c (ESX_ERROR): Likewise.
* src/esx/esx_network_driver.c (ESX_ERROR): Likewise.
* src/esx/esx_secret_driver.c (ESX_ERROR): Likewise.
* src/esx/esx_storage_driver.c (ESX_ERROR): Likewise.
* src/esx/esx_util.c (ESX_ERROR): Likewise.
* src/esx/esx_vi.c (ESX_VI_ERROR): Likewise.
* src/esx/esx_vi_methods.c (ESX_VI_ERROR): Likewise.
* src/esx/esx_vi_types.c (ESX_VI_ERROR): Likewise.
* src/esx/esx_vmx.c (ESX_ERROR): Likewise.
* src/util/hostusb.c (usbReportError): Use C99 rather than GNU
  vararg macro syntax.
* src/util/json.c (virJSONError): Likewise.
* src/util/macvtap.c (ReportError): Likewise.
* src/util/pci.c (pciReportError): Likewise.
* src/util/stats_linux.c (virStatsError): Likewise.
* src/util/util.c (virUtilError): Likewise.
* src/util/xml.c (virXMLError): Likewise.
* src/xen/proxy_internal.c (virProxyError): Use C99 rather than
  GNU vararg macro syntax.
* src/xen/sexpr.c (virSexprError): Likewise.
* src/xen/xen_driver.c (xenUnifiedError): Likewise.
* src/xen/xen_hypervisor.c (virXenError): Likewise.
* src/xen/xen_inotify.c (virXenInotifyError): Likewise.
* src/xen/xend_internal.c (virXendError): Likewise.
* src/xen/xm_internal.c (xenXMError): Likewise.
* src/xen/xs_internal.c (virXenStoreError): Likewise.
* src/cpu/cpu.h (virCPUReportError): Use C99 rather than GNU
  vararg macro syntax.
* src/datatypes.c (virLibConnError): Likewise.
* src/interface/netcf_driver.c (interfaceReportError): Likewise.
* src/libvirt.c (virLibStreamError): Likewise.
* src/lxc/lxc_conf.h (lxcError): Likewise.
* src/network/bridge_driver.c (networkReportError): Likewise.
* src/nodeinfo.c (nodeReportError): Likewise.
* src/opennebula/one_conf.h (oneError): Likewise.
* src/openvz/openvz_conf.h (openvzError): Likewise.
* src/phyp/phyp_driver.c (PHYP_ERROR): Likewise.
* src/qemu/qemu_conf.h (qemuReportError): Likewise.
* src/remote/remote_driver.c (errorf): Likewise.
* src/security/security_driver.h (virSecurityReportError): Likewise.
* src/test/test_driver.c (testError): Likewise.
* src/uml/uml_conf.h (umlReportError): Likewise.
* src/vbox/vbox_driver.c (vboxError): Likewise.
* src/vbox/vbox_tmpl.c (vboxError): Likewise.

This stops libvirt from probing for a libvirtd on the ESX server and
sets the base for the implementation of the secondary drivers.