migration/ram.c: API Conversion qemu_mutex_lock(), and qemu_mutex_unlock() to WITH_QEMU_LOCK_GUARD macro Signed-off-by: Will Gyda <vilhelmgyda@gmail.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: Fabiano Rosas <farosas@suse.de>