build: don't add C flags to RC files

This was adding a spurious `-I` to the compile flags which resulted in the
output being placed incorrectly.  Simply elide the flags for RC targets.

Author: compnerd

CoreFoundation/cmake/modules/CoreFoundationAddFramework.cmake

@@ -63,7 +63,7 @@ function(add_framework NAME)
   endif()
   target_compile_options(${NAME}
                          PRIVATE
-                           -I;${CMAKE_BINARY_DIR}/${NAME}.framework/PrivateHeaders)
+                           $<$<NOT:$<COMPILE_LANGUAGE:RC>>:-I;${CMAKE_BINARY_DIR}/${NAME}.framework/PrivateHeaders>)
   add_dependencies(${NAME} ${NAME}_POPULATE_HEADERS)
 
   if(AF_FRAMEWORK_DIRECTORY)