DebugInfo: Update test case due to dumper improvements in r195698

The dumper was only dumping one pubtypes set and it was /always/ dumping
one pubtypes set even when there were zero sets. Now that the dumper
correctly dumps zero, one, or many sets, we can update this test case to
test for the absolute absence of a set rather than a bogus/accidental
zero-valued set.
Add decorator for FreeBSD failing test due to pr18061

The test code locks mutexes from one thread and unlocks them from a
different one, which is not valid (it's either undefined behaviour or is
required to return an error).

See http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_lock.html