Fix includes of thirdparty libs which can be unbundled on Linux

Changes `builtin_icu` and `builtin_recast` to match the folder names in
`thirdparty`.

modules/vorbis/audio_stream_ogg_vorbis.cpp

@@ -32,7 +32,8 @@
 
 #include "core/io/file_access.h"
 #include "core/variant/typed_array.h"
-#include "thirdparty/libogg/ogg/ogg.h"
+
+#include <ogg/ogg.h>
 
 int AudioStreamPlaybackOggVorbis::_mix_internal(AudioFrame *p_buffer, int p_frames) {
 	ERR_FAIL_COND_V(!ready, 0);

modules/vorbis/audio_stream_ogg_vorbis.h

@@ -34,7 +34,8 @@
 #include "core/variant/variant.h"
 #include "modules/ogg/ogg_packet_sequence.h"
 #include "servers/audio/audio_stream.h"
-#include "thirdparty/libvorbis/vorbis/codec.h"
+
+#include <vorbis/codec.h>
 
 class AudioStreamOggVorbis;
 

modules/vorbis/resource_importer_ogg_vorbis.cpp

@@ -33,8 +33,9 @@
 #include "core/io/file_access.h"
 #include "core/io/resource_saver.h"
 #include "scene/resources/texture.h"
-#include "thirdparty/libogg/ogg/ogg.h"
-#include "thirdparty/libvorbis/vorbis/codec.h"
+
+#include <ogg/ogg.h>
+#include <vorbis/codec.h>
 
 #ifdef TOOLS_ENABLED
 #include "editor/import/audio_stream_import_settings.h"