audio_core: Implement a cubeb audio sink

src/audio_core/CMakeLists.txt

@@ -24,6 +24,7 @@ add_library(audio_core STATIC
     time_stretch.h
 
     $<$<BOOL:${SDL2_FOUND}>:sdl2_sink.cpp sdl2_sink.h>
+    $<$<BOOL:${ENABLE_CUBEB}>:cubeb_sink.cpp cubeb_sink.h>
 )
 
 create_target_directory_groups(audio_core)
@@ -35,3 +36,7 @@ if(SDL2_FOUND)
     target_link_libraries(audio_core PRIVATE SDL2)
     target_compile_definitions(audio_core PRIVATE HAVE_SDL2)
 endif()
+
+if(ENABLE_CUBEB)
+    target_link_libraries(audio_core PRIVATE cubeb)
+endif()