libSceCustomMusicAudioOut technical debt

sceCustomMusicAudioOutFinalize, sceCustomMusicAudioOutGetAllMusicVolume, sceCustomMusicAudioOutGetMuted, sceCustomMusicAudioOutGetVolume and sceCustomMusicAudioOutSetAllMusicVolume (libSceCustomMusicAudioOut) - names and NIDs are present in the PS5 3.20 export inventory, but no credible prototypes were found. The declarations have no parameters solely to resolve known imports; this is not an ABI claim and callers must not call them until signatures are verified