bb56bf801f
* index/li/libsdl2/libsdl2-external.toml (external): added 'homebrew'
option, "sdl2".
* index/li/libsdl2_image/libsdl2_image-external.toml: likewise, "sdl2_image".
* index/li/libsdl2_ttf/libsdl2_ttf-external.toml: likewise, "sdl2_ttf".