build: link System framework on macOS

Add `-framework System` to SDL libs and wxWidgets targets.

Signed-off-by: Rafael Kitover <rkitover@gmail.com>

cmake/Dependencies.cmake

@@ -65,6 +65,10 @@ else()
     endif()
 endif()
 
+if(APPLE)
+    list(APPEND VBAM_SDL_LIBS "-framework System")
+endif()
+
 if(ENABLE_FFMPEG)
     if(NOT FFMPEG_LIBRARIES)
         message(FATAL_ERROR "ENABLE_FFMPEG was specified, but required versions of ffmpeg libraries cannot be found!")

src/wx/CMakeLists.txt

@@ -177,6 +177,7 @@ if(CMAKE_TOOLCHAIN_FILE MATCHES "vcpkg")
 endif()
 
 if(APPLE)
+    find_library(MAC_SYSTEM System)
     find_library(COREAUDIO CoreAudio)
     find_library(COREFOUNDATION CoreFoundation)
     find_library(AUDIOTOOLBOX AudioToolbox)
@@ -359,6 +360,7 @@ function(configure_wx_target target)
 
     # Metal
     if(APPLE)
+        _add_link_libraries(${MAC_SYSTEM})
         _add_link_libraries(${COREFOUNDATION})
         _add_link_libraries(${COREAUDIO})
         _add_link_libraries(${AUDIOTOOLBOX})