gh-121617: Include string.h in pwdmodule.c if _Py_TYPEOF is undefined

If _Py_TYPEOF is undefined, Py_CLEAR falls back to an implementation with memcpy() call; conditionally include the missing string.h dependency.

Author: fuhsnn

Modules/pwdmodule.c

@@ -14,6 +14,10 @@
 #include <pwd.h>                  // getpwuid()
 #include <unistd.h>               // sysconf()
 
+#ifndef _Py_TYPEOF
+#  include <string.h>             // memcpy()
+#endif
+
 #include "clinic/pwdmodule.c.h"
 /*[clinic input]
 module pwd