Minor build system change for the Windows ports

[Steven Edwards]

Anyone got any input on this?

We need to be able to link to imports for kernel32 other then the
standard libkernel32.a. Mingw doesn't keep all of the kernel32 import
information in libkernel32.a instead it is like MSVC where it has a
libth32.a and libthunk32.a. What is needed here is a change to the build
system that allows for importing of these libs at link time when
building a dll that needs those exports. Psapi.dll needs the toolhelp
lib and one of the directx dlls needs the libthunk. I submitted a dirty
patch for this a week or two ago but it wasn't accepted. The other
option is to make the "make implib" rule and change the search path for
the import libs.  

Thanks
Steven

"Every revolution was once a thought in one man's mind"
- Ralph Waldo Emerson