cluster/afr: Set pending changelog based on filetype for new entries

        Backport of http://review.gluster.org/8506

BUG: 1136822
Change-Id: Ia864040306405acf9ebddabf63e87dc2016372dd
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/8588
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>