Initialize tzcode early.

An explicit tzset() call is usually not needed as it happens implicitly
the first time we call localtime() or mktime(), but in some cases
(sandboxing, chroot) this may be too late.

(cherry picked from commit 54d5fbe)

tcpdump.c

@@ -1560,6 +1560,13 @@ main(int argc, char **argv)
 	if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
 		error("%s", ebuf);
 
+	/*
+	 * An explicit tzset() call is usually not needed as it happens
+	 * implicitly the first time we call localtime() or mktime(),
+	 * but in some cases (sandboxing, chroot) this may be too late.
+	 */
+	tzset();
+
 	while (
 	    (op = getopt_long(argc, argv, SHORTOPTS, longopts, NULL)) != -1)
 		switch (op) {