Allow building without uadesimple [ADAPTIVE]
uadesimple has libao dependency, which is not needed if you only want to build libuade and uadecore for example. Also make pkg-config check less spammy when libao is not found.
uadesimple has libao dependency, which is not needed if you only want to build libuade and uadecore for example. Also make pkg-config check less spammy when libao is not found.