Put back the extern declaration for strdup(), between #ifndef MS_WINDOWS.

This should make everybody happy, especially since we don't say what
the argument type is (there is disagreement on that, too :-( ).

Modules/parsermodule.c

@@ -26,6 +26,9 @@
 					/* ISTERMINAL() / ISNONTERMINAL() */
 #include "compile.h"			/* PyNode_Compile()		  */
 
+#ifndef MS_WINDOWS
+char *strdup();
+#endif
 
 /*  String constants used to initialize module attributes.
  *