ec: Correctly handle xtime extended attribute

Change-Id: I2bd34f063d6bf1835d5ae57a8e9aa03f3ec3deb3
BUG: 1156404
Signed-off-by: Xavier Hernandez <xhernandez@datalab.es>
Reviewed-on: http://review.gluster.org/8972
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Dan Lambright <dlambrig@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>