porting: Enable 64bit inode properly on Darwin

Usage of -D__DARWIN_64_BIT_INO_T was wrong, use

-D_DARWIN_USE_64_BIT_INODE instead

Change-Id: I4b532232d0a61fe30f08c41ffeba50fff4ecd79e
BUG: 1089172
Signed-off-by: Harshavardhana <harsha@harshavardhana.net>
Reviewed-on: http://review.gluster.org/8219
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>