Remove libretro core - core will now be maintained by libretro

libretro have agreed to take over maintenance of the core.

Please see their fork at https://github.com/libretro/duckstation if you
wish to continue to use it.

src/common/CMakeLists.txt

@@ -179,9 +179,6 @@ endif()
 if(APPLE)
   # Needed for Vulkan Swap Chain.
   target_link_libraries(common PRIVATE "objc")
-endif()
-
-if(APPLE AND NOT BUILD_LIBRETRO_CORE)
   target_sources(common PRIVATE
     gl/context_agl.mm
     gl/context_agl.h

src/common/gl/context.cpp

@@ -11,7 +11,7 @@ Log_SetChannel(GL::Context);
 
 #if defined(WIN32) && !defined(_M_ARM64)
 #include "context_wgl.h"
-#elif defined(__APPLE__) && !defined(LIBERTRO)
+#elif defined(__APPLE__)
 #include "context_agl.h"
 #endif
 
@@ -77,7 +77,7 @@ std::unique_ptr<GL::Context> Context::Create(const WindowInfo& wi, const Version
   std::unique_ptr<Context> context;
 #if defined(WIN32) && !defined(_M_ARM64)
   context = ContextWGL::Create(wi, versions_to_try, num_versions_to_try);
-#elif defined(__APPLE__) && !defined(LIBRETRO)
+#elif defined(__APPLE__)
   context = ContextAGL::Create(wi, versions_to_try, num_versions_to_try);
 #elif defined(ANDROID)
 #ifdef USE_EGL

src/common/vulkan/shader_compiler.cpp

@@ -124,9 +124,7 @@ bool InitializeGlslang()
     return false;
   }
 
-#ifndef LIBRETRO
   std::atexit([]() { glslang::FinalizeProcess(); });
-#endif
 
   glslang_initialized = true;
   return true;

src/common/window_info.h

@@ -12,7 +12,6 @@ struct WindowInfo
     Wayland,
     MacOS,
     Android,
-    Libretro,
   };
 
   enum class SurfaceFormat