build: prefer SWIFT_SDK_*_OBJECT_FORMAT

Fix another instance of a SDK target check in favour of the object format check.

Author: compnerd

cmake/modules/AddSwift.cmake

@@ -647,8 +647,7 @@ function(_add_swift_library_single target name)
 
   # The section metadata objects are generated sources, and we need to tell CMake
   # not to expect to find them prior to their generation.
-  if("${SWIFTLIB_SINGLE_SDK}" STREQUAL "LINUX" OR
-     "${SWIFTLIB_SINGLE_SDK}" STREQUAL "FREEBSD")
+  if("${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_OBJECT_FORMAT}" STREQUAL "ELF")
     if("${libkind}" STREQUAL "SHARED")
       set_source_files_properties(${SWIFT_SECTIONS_OBJECT_BEGIN} PROPERTIES GENERATED 1)
       set_source_files_properties(${SWIFT_SECTIONS_OBJECT_END} PROPERTIES GENERATED 1)