build: ensure that we push -static into the flags

The CxxStdlib module is built statically only.  We would previously
build the static library but indicate dynamic linking.  This would
incorrectly code generate in the client on Windows making it impossible
to use the module.

Author: compnerd

stdlib/cmake/modules/SwiftSource.cmake

@@ -455,6 +455,10 @@ function(_compile_swift_files
       MACCATALYST_BUILD_FLAVOR "${maccatalyst_build_flavor}"
       )
 
+  if(SWIFTFILE_STATIC)
+    list(APPEND swift_flags -static)
+  endif()
+
   # Determine the subdirectory where the binary should be placed.
   set(library_subdir_sdk "${SWIFTFILE_SDK}")
   if(maccatalyst_build_flavor STREQUAL "ios-like")