Fix module entry deallocation in MODULE_DecRefCount

[Warren_Baird at cimmetry.com]

>the fix doesn't seem the right one... could you post a -debugmsg
>+file,+module of what really happens here

The places I've seen it happen are in parts of a large and complicated program -
I'll see if I can find a simple test case that repros the problem and post a
trace here.

But I can give you more details on what I found happening...   After calling
LoadLibrary("foo") there were two entries for library foo in the
MODULE_modref_list.  When you unloaded the library the first entry found was
removed, but the 2nd entry remained, but the memory behind it didn't exist any
more.  If you tried to load the library again, the loading code would find the
entry in the modref list and try to reuse it, and immediately segfault...  I
seem to recall that the first entry had the correct path to the library, and the
send entry had "C:\windows\system\foo.dll" or something like that...

Note that I've only observed this on a sparc/solaris system - it may be due to a
pecularity of the way libs are loaded there...

If I can repro it with a simple enough case to generate a reasonably sized log,
I'll post it here, hopefully tomorrow...

Warren