MFC: r255284

MFC: r255284
It was reported via email that the cu_sent field used by the
krpc client side UDP was observed as way out of range and
caused the rpc.lockd daemon to hang trying to do an RPC.
Inspection of the code found two places where the RPC request
is re-queued, but the value of cu_sent was not incremented.
Since cu_sent is always decremented when the RPC request is
dequeued, I think this could have caused cu_sent to go out of
range. This patch adds lines to increment cu_sent for these
two cases.

git-svn-id: svn://svn.freebsd.org/base/stable/9@255770 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f