scripts: ensure monitor socket has SO_REUSEADDR set

If tests use a TCP based monitor socket, the connection will
go into a TIMED_WAIT state when the test exits. This will
randomly prevent the test from being re-run without a certain
time period. Set the SO_REUSEADDR flag on the socket to ensure
we can immediately re-run the tests

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1469020993-29426-6-git-send-email-berrange@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
