Debugger unhappiness blocking valgrind runs

[Dan Kegel]

I just tried to do another daily valgrind run, but
it got blocked because it started up an infinite
number of copies of winedbg.  It seems that
a crash in the imagelist test in GetDibBits
triggered winedbg, and winedbg crashed trying
to generate a backtrace, which of course fired
up winedbg, which... was bad.  Some of the logs
are at
http://bugs.winehq.org/show_bug.cgi?id=11211

This seems to be very recent breakage, either today or yesterday.
- Dan