jvmti patch for mingw32

[Tom Tromey]

>>>>> "Mohan" == Mohan Embar <gnustuff@thisiscool.com> writes:

>> Building for mingw32 is currently broken at multiple places. This is the 
>> first patch. I'll see if I can fix the others as well...

Mohan> Are the other broken places similar missing JNICALL declarations
Mohan> or other issues? If they are similar missing declarations, can you
Mohan> combine them into one patch? Thanks for looking into this. If you
Mohan> create a proper ChangeLog, I'll check this in if no one else does.

I'm doing a build here with that patch in place.  I also made that
function 'static'.  I'll commit when the build is done.

Tom