The Cosmopolitan-specific windows.h stuff has now been moved to an
external file in the extras folder:

    extras/cosmopolitan/include/windows.h

To compile with Cosmpolitan it is now required that you add the above
path to the command line when compiling.

The Windows build now compilers with this commit.

This is just an experiment. Cosmopolitan is not officially being
supported.

The Windows build does not compile with this commit.

Public issue https://github.com/mackron/miniaudio/issues/495

Public issue https://github.com/mackron/miniaudio/discussions/637

This will be expanded on later to be a lot more complete.

Public issue https://github.com/mackron/miniaudio/issues/597.