Instead of that change, simply undefine putenv in the test program.
-#serial 12
+#serial 13
dnl This macro is intended to be used solely in this file.
dnl These are the prerequisite macros for GNU's strftime.c replacement.
time_t t = 738367; /* Fri Jan 9 13:06:07 1970 */
tm = gmtime (&t);
+ /* Undefine this in case the configure-time putenv test has defined it
+ to something else. The use we make of this function here doesn't
+ require the added functionality of the replacement one. */
+#undef putenv
+
/* This is necessary to make strftime give consistent zone strings and
e.g., seconds since the epoch (%s). */
putenv ("TZ=GMT0");