glusterd: Allow symlink parent for snap_mount_folder

If '/var' is a symlink which is on OSX, 'glusterd'
initialization fails which is not necessary fix it.

Change-Id: I83adc16cfc0e0deaa18acf74ba99299ba4a21d60
BUG: 1061685
Signed-off-by: Harshavardhana <harsha@harshavardhana.net>
Reviewed-on: http://review.gluster.org/7558
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>