[PATCH] Upgrade to 'threads' 1.74

Attached patch upgrade 'blead' to 'threads' 1.74:
	- Updated DESCRIPTION in POD
	- Added 'no_threads' test for non-threaded Perls

The newly added test allows non-threaded Perls to install 'threads'
with a 'PASS' instead of the ambiguous 'UNKNOWN'.

• [PATCH] Upgrade to 'threads' 1.74 by Jerry D. Hedden
• Re: [PATCH] Upgrade to 'threads' 1.74 by H.Merijn Brand