I'm trying to read the patch. It contains many interesting things (and others I have no opinon about), but it is very large, and makes it difficult to comment or find why some change were made etc.

I do believe that better supporting the mingw32 platform is a worthy goal, but a single large patch, even after review, is something difficult to trust.

I suggest to present this work in another form. Maybe something like a Mercurial Patch Queue?  This would give us a collection of smaller patches, each with its own interest.  Each one can be discussed, modified, reviewed separately and by different people. Large easy tasks (like a massive rename) are distinct from small-but-hard changes. And when something is updated, the reviewers don't have to parse the whole file again; they just look at the recent patches.

As an example: among the many changes, you had to handle the Modules/getpath.c vs. PC/getpathp.c inconsistency.  You chose to have both filenames in the Makefile, but in my opinion it would be better to try to merge the files.