Sorry, I meant this part of the patch:

diff --git a/Modules/_ctypes/libffi_osx/x86/x86-ffi_darwin.c b/Modules/_ctypes/libffi_osx/
--- a/Modules/_ctypes/libffi_osx/x86/x86-ffi_darwin.c
+++ b/Modules/_ctypes/libffi_osx/x86/x86-ffi_darwin.c
@@ -35,6 +35,8 @@
 /* ffi_prep_args is called by the assembly routine once stack space
  has been allocated for the function's arguments */
 
+void ffi_prep_args(char *stack, extended_cif *ecif);
+
 void ffi_prep_args(char *stack, extended_cif *ecif)
 {
     register unsigned int i;