Cross-build the SDL

[corwinn]

Prepare build scripts. Read the license info. Add questions. Etc. . The cross-compile adventure never ends.

[corwinn]

Done.

• SDL2 x86_64-w64-mingw32-windres_wrapper SDL2-2.26.2_cmake_toolchain cmake ../SDL2-2.26.2 -DSDL_STATIC_PIC=ON -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$P -DSDL2_DISABLE_SDL2MAIN=OFF -DCMAKE_TOOLCHAIN_FILE=../SDL2-2.26.2_cmake_toolchain -DCMAKE_CROSSCOMPILING=True Not using libSDL2main.a <=> compile -DSDL_MAIN_HANDLED and define my own WinMain.
• SDL2_mixer cmake ../SDL2_mixer-2.6.2 -DSDL_STATIC_PIC=ON -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$P -DCMAKE_TOOLCHAIN_FILE=../SDL2-2.26.2_cmake_toolchain -DCMAKE_CROSSCOMPILING=True -DSDL2MIXER_OPUS=OFF -DSDL2MIXER_FLAC=ON -DSDL2MIXER_FLAC_LIBFLAC=OFF -DSDL2MIXER_MOD=OFF -DSDL2MIXER_MIDI=OFF -DSDL2MIXER_FLAC_DRFLAC=ON