Problem:  After add brick to a distribute volume to convert to replica is not
          triggering self heal.

Solution: Modify the condition in brick_graph_add_index to set trusted.afr.dirty
          attribute in xlator.

Test    : To verify the patch followd below steps
          1) Create a single node volume
             gluster volume create <DIS> <IP:/dist1/brick1>
          2) Start volume and create mount point
             mount -t glusterfs <IP>:/DIS /mnt
          3) Touch some file and write some data on file
          4) Add another brick along with replica 2
             gluster volume add-brick DIS replica 2 <IP>:/dist2/brick2
          5) Before apply the patch file size is 0 bytes in mount point.
Backport of commit 87bb8d0400d4ed18dd3954b1d9e5ca6ee0fb9742
BUG: 1366444
Signed-off-by: Mohit Agrawal <moagrawa@redhat.com>

> Change-Id: Ief0ccbf98ea21b53d0e27edef177db6cabb3397f
> Signed-off-by: Mohit Agrawal <moagrawa@redhat.com>
> Reviewed-on: http://review.gluster.org/15118
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> Reviewed-by: Ravishankar N <ravishankar@redhat.com>
> Reviewed-by: Anuradha Talur <atalur@redhat.com>
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
> (cherry picked from commit 87bb8d0400d4ed18dd3954b1d9e5ca6ee0fb9742)

Change-Id: I9c21ba4d7b1a2d7c5c79a6bb86cc05831b0cd120
Reviewed-on: http://review.gluster.org/15152
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Tested-by: Atin Mukherjee <amukherj@redhat.com>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>