Re-factor the code from networkEnableIpForwarding() into a
utility function in preparation for code which writes to
sysfs files.

* qemud/qemud.c (GET_CONF_STR): Use virStrerror, not strerror.
* qemud/remote.c (remoteDispatchDomainBlockPeek): Likewise.
(remoteDispatchDomainMemoryPeek, remoteDispatchAuthSaslInit): Likewise.
(remoteDispatchAuthPolkit): Likewise.
* src/lxc_container.c (lxcContainerAvailable): Likewise.
* src/network_driver.c (networkStartNetworkDaemon): Likewise.
(networkShutdownNetworkDaemon): Likewise.
* src/qemu_conf.c (qemudExtractVersion, qemudNetworkIfaceConnect):
* src/storage_conf.c (virStoragePoolLoadAllConfigs): Likewise.
* src/storage_driver.c (storagePoolUndefine): Likewise.
* src/uml_driver.c (umlStartup, umlStartVMDaemon): Likewise.
* src/util.c (virFileReadAll): Likewise.
* src/uuid.c (virUUIDGenerate): Likewise.
* src/xen_internal.c (get_cpu_flags): Likewise.

* src/uml_conf.c (VIR_FROM_THIS): Define to VIR_FROM_UML.
* src/xs_internal.c (VIR_FROM_THIS): Define to VIR_FROM_XEN.
* src/xml.c (VIR_FROM_THIS): Define to VIR_FROM_XML.
* src/stats_linux.c (VIR_FROM_THIS): Define to VIR_FROM_STATS_LINUX.
* src/datatypes.c (VIR_FROM_THIS): Define to VIR_FROM_NONE.
* src/lxc_conf.c (VIR_FROM_THIS): Define to VIR_FROM_LXC.
* src/libvirt.c (VIR_FROM_THIS): Define to VIR_FROM_NONE.
* src/node_device_conf.c (VIR_FROM_THIS): Define to VIR_FROM_NODEDEV.
* src/openvz_conf.c (VIR_FROM_THIS): Define to VIR_FROM_OPENVZ.
* src/openvz_driver.c (VIR_FROM_THIS): Define to VIR_FROM_OPENVZ.
* src/conf.c (VIR_FROM_THIS): Define to VIR_FROM_CONF.
Note: this loses config_filename:config_lineno diagnostics,
but that's ok.
* src/node_device.c (VIR_FROM_THIS): Define to VIR_FROM_NODEDEV.
* src/sexpr.c (VIR_FROM_THIS): Define to VIR_FROM_SEXPR.
* po/POTFILES.in: remove src/sexpr.c and src/lxc_conf.c

* src/network_driver.c (networkEnableIpForwarding): This function
would always return 1 (success).  Now it returns 0 upon write or
close failure, being careful to preserve any errno from a write failure.
Add comments.

storage XML to libvirtd, which was saved in /etc/libvirt/storage.  On subsequent
stop/start of libvirtd, because of another bug , an
error wasn't being set properly in an error path, so libvirtd was SEGV'ing in
storage_conf.c:virStoragePoolObjLoad when trying to dereference the NULL err
returned from virGetLastError().  Make this more robust against errors by always
doing "err ? err->message : NULL" in the printf.  I looked around the tree and
found a couple of other places that weren't guarded, so this patch fixes them as
well.
Signed-off-by: NChris Lalancette <clalance@redhat.com>

POTFILES.in.  Add it there, and then fix up one warning about included
c-ctypes.h that wasn't being used.
Signed-off-by: NChris Lalancette <clalance@redhat.com>