emulators/ppsspp: Update to 1.18.1

• Use to multimedia/ffmpeg3 for compatibility and stability
• Submitter becomes maintainer

Changelog: https://www.ppsspp.org/news/release-1.18/

Reset PORTREVISION for slave ports, emulators/libretro-ppsspp and
emulators/ppsspp-qt5

PR: 282792