Virsh uses an error handler to save errors from libvirt. On some code
paths it's needed to clear libvirt errors and continue on fallback code
paths without reporting failure.
This patch adds function vshResetLibvirtError() that clears error
returned by libvirt and updates all places where the old two-line method
was used.
Commands to manage network are moved from virsh.c to virsh-network.c,
with a few helpers for network command use.
* virsh.c: Remove network commands and a few helpers.
* virsh-network.c: New file, filled with network commands and its
helpers.
* po/POTFILES.in: Add virsh-network.c
* cfg.mk: Skip to check config.h including for virsh-network.c
