Use INTERFACE_INCLUDE_DIRECTORIES in Xcode's sdl2-config.cmake

Xcode/SDL/pkg-support/resources/CMake/sdl2-config.cmake

@@ -43,5 +43,6 @@ if(NOT TARGET SDL2::SDL2)
         PROPERTIES
             FRAMEWORK 1
             IMPORTED_LOCATION "${SDL2_LIBRARY}"
+            INTERFACE_INCLUDE_DIRECTORIES "${SDL2_INCLUDE_DIR}"
     )
 endif()