fix warnings reported by -Wshadow.
fix warnings reported by -Wshadow.

OpenMusicKontrollers/synthpod,OpenMusicKontrollers/synthpod,OpenMusicKontrollers/synthpod,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/libosc,OpenMusicKontrollers/chimaera.lv2,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/chimaera.lv2,OpenMusicKontrollers/eteroj.lv2,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/synthpod,OpenMusicKontrollers/chimaerad,OpenMusicKontrollers/eteroj.lv2,OpenMusicKontrollers/synthpod,OpenMusicKontrollers/chimaerad