Signal handling and SuspendThread

[Max Kaehn]

The latest snapshot (cygwin1-20060103.dll) does not have the "CPU
hogging" behavior-- we ran a bunch of parallelized mysql builds through
without seeing that problem reproduce.  Thanks!

There's still a deadlock of some sort going on in the build (mysql) that
found the last problem, but it might be in a completely different place.
(It's somewhere in a bash script that invokes gcc-- the problem might
not even be in cygwin.)  I'm trying to track it down right now.