cluster/afr: Disable eager-lock if open-fd-count > 1

Lets say mount1 has eager-lock(full-lock) and after the eager-lock
is taken mount2 opened the same file, it won't be able to
perform any data operations until mount1 releases eager-lock.
To avoid such scenario do not enable eager-lock for transaction
if open-fd-count is > 1. Delaying of changelog piggybacking is
avoided in this situation.

Change-Id: I51b45d6a7c216a78860aff0265a0b8dabc6423a5
BUG: 910217
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/5432
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: venkatesh somyajulu <vsomyaju@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>