Posix/readdirp : Avoid filling wrong stat info for dentry in readdirp

Problem:  Upon no entry found for a dentry, posix_readdirp_fill
          used to fill the stat for the current entry with the
          previous one.

Solution: Continue with other entries if lstat failed for current
          one

Change-Id: Ic96b5900451ed6c8de59acf9fee2e116649d3cdb
BUG: 1096578
Signed-off-by: Susant Palai <spalai@redhat.com>
Reviewed-on: http://review.gluster.org/7733
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>