nfs-utils: introduce new statd testing simulator

nfs-utils: introduce new statd testing simulator

rpc.statd is often prone to subtle, difficult to detect breakage. When
it has problems, they're often invisible and only manifest themselves
as failed lock recovery.

This program is intended to function as part of a test harness for
statd. It's a multicall binary that serves as a synthetic NSM client
program, and a daemon that can simulate lockd for purposes of testing
the NSM to NLM downcall.

A new top level "tests/" directory is also added to nfs-utils to start
as a repository for automated tests of nfs-utils components.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>