Revert "Add thread mutex deadlock checker script to tests/."

Revert "Add thread mutex deadlock checker script to tests/."

This reverts commit b3c7a0769f6d11a3125693b7c8fd1ab13746ea09.

It wasn't working the way I was hoping. Most of the pwmc clients
weren't connecting successfully. The shell fragment below does a
decent enough job although the total number of clients may need to be
adjusted to avoid any "too many open files" errors:

	 time { for i in `seq 1 1000`; do { sh -c 'echo -ne LIST | \
	      pwmc --quiet new >/dev/null || \
	      echo "pwmc error" && break &'; }; done; } &

Then watch the pwmd logs for connections. The pwmc error from the
original commit was a failure to connect to pwmd. I'm not sure what
the cause is but the above fragment can queue 200+ connected clients
depending on the cache status. I will make a better test case some
other time.