ensure writes are flushed in run lock IPC
set sync=true on IPC in run lock tests
fix race in test setup

the heart of the test is confirming that the last 2 messages are p1
releasing lock and then p2 acquiring it. The two messages confirm that
the test case is set up correctly.
remove setup message, it's a race either way
Merge branch 'more-runlock-fixes' into 11-stable