Fix DECREF name clash

MinGW's winnt.h also defines DECREF.
Regenerate charmonizer.c for MinGW
Update .gitignore for MinGW
Fix intermittent test-only sort order bug.

Lucy breaks ties by doc_id, but the test did not.  The bug only manifested
once every few hundred iterations because the collisions between scores
occurred rarely.
Increase randomness of HitQueue test.

Insert docs into HitQueue in random order to stress the heap sort, even
though they will be inserted in doc_id order in current Lucy.
Add missing chy_ prefix

Fixes Cygwin build.
Update .gitignore for Cygwin
Regen charmonizer for robust removal on Win.
Replace dicey POD with comments.

The pod-checker test didn't like the existing source, so use ordinary line
comments to disable code instead.