1. Make the output deterministic; different thread interleaving from expected
was causing failures for me.
2. Make it actually use the condition variable -- the condvar stupidly wasn't
actually being used in the expected case, because the other threads finished
all their work before pthread_cond_wait() even got called, and this prevented
the condition guarding pthread_cond_wait() from succeeding.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2952
