opus: Move public headers to match system install

(cherry picked from commit 611a94e3a673a61b51746366366c698c66ef0195)

modules/opus/SCsub

@@ -201,6 +201,7 @@ if (env['builtin_opus'] != 'no'):
     thirdparty_include_paths = [
         "",
         "celt",
+        "opus",
         "silk",
         "silk/fixed",
         "silk/float",

modules/opus/audio_stream_opus.h

@@ -36,7 +36,7 @@
 #include "os/file_access.h"
 #include "scene/resources/audio_stream.h"
 
-#include <opusfile.h>
+#include <opus/opusfile.h>
 
 class AudioStreamPlaybackOpus : public AudioStreamPlayback {
 

thirdparty/README.md

@@ -128,7 +128,7 @@ Files extracted from upstream source:
 
 - all .c and .h files in src/ (both opus and opusfile),
   except `opus_demo.c`
-- all .h files in include/ (both opus and opusfile)
+- all .h files in include/ (both opus and opusfile) as opus/
 - COPYING