0.8.4.40

0.8.4.40
	Removed debugging message about unexpectedly enabled signals.
	These days we're older and wiser and expect that stuff to
	happen

	contrib/experimental-thread.patch, as the name suggests, is
	a patch that may help thread stability problems, but hasn't
	been sufficiently well tested to get merged into SBCL proper
	this late int he release cycle