GFS2: use _RET_IP_ instead of (unsigned long)__builtin_return_address(0)

use macro definition

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

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

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

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