Revert "Strip Alpha from PNGs"
Revert "Strip Alpha from PNGs"

This reverts commit 2a9794dd84575e637ae9f55b0c0ad4b355b24107.

The commit that made Dolphin stop outputting alpha was merged
5 years ago, so there's no longer much reason to keep this around.

The main reason why I want to revert this is because the code doesn't
actually work right now due to imagemagick not being installed.

dolphin-emu/fifoci,dolphin-emu/fifoci,dolphin-emu/fifoci