lxc: Refresh capabilities if they have never been initalized
lxc: Refresh capabilities if they have never been initalized

Adjust virLXCDriverGetCapabilities to fill in driver->caps if it is
empty, regardless of the passed 'refresh' value. This matches the
pattern used in virQEMUDriverGetCapabilities

This fixes LXC XML startup parsing for me

Reviewed-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>
Signed-off-by: Cole Robinson <7cd45ff6ad1fb7cf556a02797d774247851499f8@redhat.com>

nertpinx/libvirt,olafhering/libvirt,libvirt/libvirt,fabianfreyer/libvirt,libvirt/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,libvirt/libvirt,nertpinx/libvirt,olafhering/libvirt,jardasgit/libvirt,jfehlig/libvirt,zippy2/libvirt,jardasgit/libvirt,zippy2/libvirt,jardasgit/libvirt,zippy2/libvirt,crobinso/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,crobinso/libvirt,fabianfreyer/libvirt,crobinso/libvirt,jfehlig/libvirt,crobinso/libvirt,olafhering/libvirt,jfehlig/libvirt,jardasgit/libvirt,libvirt/libvirt,jardasgit/libvirt,zippy2/libvirt,olafhering/libvirt,nertpinx/libvirt