Apply the CMake Apple Silicon workaround for the 'FREESTANDING' SDK too (#38956)

Author: kubamracek

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -2066,14 +2066,18 @@ function(add_swift_target_library name)
         endif()
       endif()
 
-      if(sdk IN_LIST SWIFT_APPLE_PLATFORMS)
+      if((sdk IN_LIST SWIFT_APPLE_PLATFORMS)
+        OR (sdk STREQUAL "FREESTANDING"))
         # In the past, we relied on unsetting globally
         # CMAKE_OSX_ARCHITECTURES to ensure that CMake would
         # not add the -arch flag
         # This is no longer the case when running on Apple Silicon,
         # when CMake will enforce a default (see
         # https://gitlab.kitware.com/cmake/cmake/-/merge_requests/5291)
         set_property(TARGET ${VARIANT_NAME} PROPERTY OSX_ARCHITECTURES "${arch}")
+        if (SWIFTLIB_IS_STDLIB AND SWIFTLIB_STATIC)
+          set_property(TARGET ${VARIANT_NAME}-static PROPERTY OSX_ARCHITECTURES "${arch}")
+        endif()
       endif()
     endforeach()
 
@@ -2512,7 +2516,8 @@ function(add_swift_target_executable name)
           EXCLUDE_FROM_ALL TRUE)
       endif()
 
-      if(${sdk} IN_LIST SWIFT_APPLE_PLATFORMS)
+      if((${sdk} IN_LIST SWIFT_APPLE_PLATFORMS)
+        OR (sdk STREQUAL "FREESTANDING"))
         # In the past, we relied on unsetting globally
         # CMAKE_OSX_ARCHITECTURES to ensure that CMake would
         # not add the -arch flag