Merge branch 'master' of https://github.com/rdp/ffmpeg-windows-build-helpers

Conflicts:
	cross_compile_ffmpeg.shfix a case of .tar.gz package actually being .tar
Merge branch 'master' of https://github.com/rdp/ffmpeg-windows-build-helpers
Merge commit '8213d385b5321ac2c36ddd06c889cc7365d0a3ce'