heal: fix the way we check the presence of AFR in glfsheal

Problem:
glfsh_validate_replicate_volume() used to check if AFR was the parent of
all client xlators present in the graph. This need not always be true, for
example, for user-serviceable-snapshots where the parent of snapd-client is
snapview-client.

Fix:
glfsh_validate_replicate_volume() returns true if atleast one client
xlator has AFR as its parent. Also, AFR need not be its immediate
parent, but be present somewhere in its parent ancestry.

Change-Id: Id37ac88c3202bb2fdcae56e108adc461dc8a9a37
BUG: 1115950
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-on: http://review.gluster.org/8229
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>