ec: Add state dump support

This is a backport of http://review.gluster.org/8891/

Change-Id: I4504f3050674dde217e79af28cb4d2b5370fe2d5
BUG: 1148093
Signed-off-by: Xavier Hernandez <xhernandez@datalab.es>
Reviewed-on: http://review.gluster.org/8899
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Dan Lambright <dlambrig@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>