2 - Testsuite: In the util/threads test no longer free the test_mutex
3 before all worker threads have finished.
4 - Testsuite: The master thread could starve the worker threads quite
5 badly on certain systems, causing them to run only partially in
6 the allowed window. This resulted in test failures. Now the master
7 thread sleeps occasionally for a few microseconds while the two
8 worker-threads compete for the mutex.