These scripts can be used to cross-compile busybox-w32 on a
Fedora Linux system with mingw-w64 and llvm-mingw toolchains.
The former are available from the Fedora repositories; the
latter needs to be downloaded and installed from:

   https://github.com/mstorsjo/llvm-mingw

The release build performs some additional optimisation and is
slightly slower as a result.

The busybox-w32 help message includes information about the build
platform.  Obtaining this information is very specific to the
platform used.