criu-log.h: fit macros in 80 columns

Before this patch, backslash was at 81th column which makes the text
twice longer on a standard 80 col terminal, which is quite annoying.
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>