0.8.9.45:

0.8.9.45:
	Slight threadcode cleanup
	... add boilerplate;
	... make bodies of WITH-MUTEX and WITH-RECURSIVE-LOCK accept
		declarations;
	... implement GET-MUTEX and RELEASE-MUTEX for unithread, but
		don't actually use them yet because we're still in
		"no performance penalty for unithread";
	... make WITH-MUTEX available in the cross-compiler, so that
		if necessary we can lock sections non-recursively.