Symlink mtime changes when rebalancing

Added mtime preservation for special files during rebalance.

Change-Id: If04921d4d66853fde8b4d8a3ab748790864f8f42
BUG: 1122443
Signed-off-by: Anders Blomdell <anders.blomdell@control.lth.se>
Reviewed-on: http://review.gluster.org/8383
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>
Reviewed-by: Harshavardhana <harsha@harshavardhana.net>
Reviewed-by: Anand Avati <avati@redhat.com>