Modify blocking test cases to not proceed without waiting for service

A blocking write of queue size is added to all blocking
test cases to ensure that the blocking read by service
gets completed before the client moves on to the next
test case.

Bug: 63825555
Test: fmq_test

Change-Id: I51a55e57c4f58cd4d066c54cbe52745282eaef19
1 file changed