ec: Correctly handle quota xattrs

This is a backport of http://review.gluster.org/8990/

Change-Id: I35e11d83c318210d44b918e847cf13db35b01510
BUG: 1158088
Signed-off-by: Xavier Hernandez <xhernandez@datalab.es>
Reviewed-on: http://review.gluster.org/8992
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Dan Lambright <dlambrig@redhat.com>