Allow to specify a proxy to be used by libcurl.

Pass a struct containing the parameters instead of passing each
one individually. This make future extensions a bit simpler.

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.

* .gnulib: Update to latest.
* bootstrap.conf (gnulib_modules): Import netdb.
* src/esx/esx_util.c (AI_ADDRCONFIG): Rely on gnulib.
* src/remote/remote_driver.c (AI_ADDRCONFIG): Likewise.
* tools/virsh.c (WEXITSTATUS, O_SYNC): Likewise.

This also fixes a portability problem with the %a format modifier.
%a is not portable and made esxDomainDumpXML fail at runtime in
MinGW builds.

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.

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.

Questions can block tasks, to handle them automatically the driver can answers
them with the default answer. The auto_answer query parameter allows to enable
this automatic question handling.

* src/esx/README: add a detailed explanation for automatic question handling
* src/esx/esx_driver.c: add automatic question handling for all task related
  driver functions
* src/esx/esx_util.[ch]: add handling for the auto_answer query parameter
* src/esx/esx_vi.[ch], src/esx/esx_vi_methods.[ch], src/esx/esx_vi_types.[ch]:
  add new VI API methods and types and additional helper functions for
  automatic question handling

* src/esx/esx_util.c (esxUtil_ParseDatastoreRelatedPath): Return
right away for invalid inputs, rather than using them (which would
dereference NULL pointers) in clean-up code.

* src/esx/esx_util.[ch]: remove esxUtil_EqualSuffix()
* src/esx/esx_driver.c, src/esx/esx_vmx.c: replace esxUtil_EqualSuffix()
  with virFileHasSuffix()

A given domain XML gets converted to a VMX config, uploaded to the host
and registered as new virtual machine.

* src/esx/esx_driver.c: refactor datastore related path parsing into
  esxUtil_ParseDatastoreRelatedPath()
* src/esx/esx_util.[ch]: add esxUtil_ParseDatastoreRelatedPath()
* src/esx/esx_vi.[ch]: add esxVI_Context_UploadFile(), add datastores to
  the traversal in esxVI_BuildFullTraversalSpecList(), add
  esxVI_LookupDatastoreByName()
* src/esx/esx_vi_methods.[ch]: add esxVI_RegisterVM_Task()
* src/esx/esx_vi_types.c: make some error message more verbose
* src/esx/esx_vmx.[ch]: add esxVMX_AbsolutePathToDatastoreRelatedPath()
  to convert a path into a datastore related path, add esxVMX_ParseFileName()
  to convert from VMX path format to domain XML path format, extend the other
  parsing function to be datastore aware, add esxVMX_FormatFileName() to
  convert from domain XML path format to VMX path format, fix VMX ethernet
  entry formating
* tests/esxutilstest.c: add test for esxUtil_ParseDatastoreRelatedPath()
* tests/vmx2xmldata/*: update domain XML files to use datastore related paths
* tests/xml2vmxdata/*: update domain XML files to use datastore related paths,
  update VMX files to use absolute paths

This enables the auth callback to automatically distinguish between
requests for ESX host and vCenter credentials.

* src/esx/esx_util.[ch]: set challenge for auth callback to hostname

* src/esx/esx_util.c: let esxUtil_GetConfigUUID() report an error if
  virUUIDParse() fails

* src/esx/esx_util.c: esxUtil_ParseQuery() warns if a known query
  parameter should be ignored due to the corresponding char/int pointer
  being NULL, instead of silently ignoring it. Fix the control flow.

* src/esx/esx_driver.c src/esx/esx_util.[ch] src/esx/esx_vi.[ch]:
  just a name change

* autobuild.sh, mingw32-libvirt.spec.in: Enable esx on mingw32
* src/esx/esx_driver.c: Define AI_ADDRCONFIG if not set
* src/esx/esx_util.c, src/esx/esx_vi_types.c: Always use
  %lld & friends, since gnulib guarentees we have these
  and not the target's own variants

* src/esx/esx_driver.c src/esx/esx_util.c src/esx/esx_util.h
  src/esx/esx_vi.c src/esx/esx_vi.h: adds a no_verify query parameter to
  stop libcurl from verifying theserver certificate for the https
  transport.

* src/esx/esx_*.[ch]: the driver, uses a remote minimal SOAP client
  to talk to the VI services on ESX nodes.
* configure.in include/libvirt/virterror.h src/Makefile.am src/driver.h
  src/libvirt.c src/virterror.c: glue in the new driver