[GFS2] Move gfs2_logd into log.c

This means that we can mark gfs2_ail1_empty static and prepares
the way for further changes.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --cc fs/gfs2/daemon.c
Simple merge

diff --cc fs/gfs2/daemon.h
Simple merge

diff --cc fs/gfs2/log.c
Simple merge

diff --cc fs/gfs2/log.h
Simple merge