glfs_fini: Fix a possible hang in glfs_fini.

glfs_fini is called when there is a failure in glfs_new,
glfs_init etc. If an application sees a failure in glfs_new
and calls glfs_fini, it will result in hang in glfs_fini.

Fixed the hang.

Change-Id: I80b52cd76d1d7f3fe9a10a91b7226d54176a8982
BUG: 1091335
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: http://review.gluster.org/7857
Reviewed-by: soumya k <skoduri@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>