Support unicode paths in installed.txt.

The only caveat is it has to be saved as a UTF-8 file or it won't work properly. This will probably conflict with https://github.com/unknownbrackets/ppsspp/commit/1311c4939a88dbed6e279c6f77bd18a25ffb0d24 from https://github.com/hrydgard/ppsspp/pull/4170.