ogg/vorbis/opus: Make them modules and unbundle thirdparty libs

Took the opportunity to undo the Godot changed made to the
opus source. The opus module should eventually be built in its
own environment to avoid polluting others with too many include
dirs and defines.

TODO: Fix the platform/ stuff for opus.

modules/ogg/config.py

@@ -0,0 +1,6 @@
+
+def can_build(platform):
+	return True
+
+def configure(env):
+	pass