[RFC PATCH] lib/vsprintf.c: Simplify uuid_string()

From: George Spelvin
Date: Mon May 11 2015 - 12:32:40 EST

I didn't see your decimal print changes before they went in, but great
work! That's a real "why didn't I think of that?" change.

Anyway, merging some local patches I have with that prompted me to look
over that file and I came up with the following two patches which might
be interesting. RFC until I build a test harness and made sure there
aren't any stupid bugs, but the ideas are simple enough.

They're so small I'm breaking protocol and including them both in the same