GNU make looks first for a file called GNUmakefile, ahead of
looking for Makefile and then makefile.
Renaming sys/windows/Makefile.mingw32 to sys/windows/GNUmakefile
allows:
o src/GNUmakefile (for use by GNU make) and src/Makefile (for use
Microsoft nmake) to both reside in the src folder during build.
o src/GNUmakefile will be used by GNU make, without having to
explicitly specify "-f GNUmakefile" on the GNU make command line.
o src/Makefile will be used by Microsoft nmake, without having to
explicitly specify "-f Makefile" on the Microsoft nmake command line.
For the gcc build, the movemement of sys/windows/GNUmakefile needs
to be copied to src/GNUmakefile as part of the build process (see
sys/windows/build-msys2.txt).
For the Microsoft Visual Studio command line build with nmake,
sys/windows/Makefile.nmake needs to be copied to src/Makefile as
part of the build process (see sys/windows/build-nmake.txt).
They are both copied to the src folder from their respective
repository source file names when the nhsetup.bat file is used.
Update makdefs source and its man page.
Remove all mentions of the vision table files from:
o .gitattributes
o .gitignore
o Files
o Cross-compiling
Add a brief note in the fixes file.
