This patch is untested!

diff -Naur gawk-3.1.6.orig/builtin.c gawk-3.1.6.arc4/builtin.c
--- gawk-3.1.6.orig/builtin.c	2007-09-30 15:57:05.000000000 -0400
+++ gawk-3.1.6.arc4/builtin.c	2007-11-25 21:21:57.000000000 -0500
@@ -2064,7 +2064,7 @@
 	}
 
 	if (tree == NULL)
-		srandom((unsigned int) (save_seed = (long) time((time_t *) 0)));
+		srandom((unsigned int) (save_seed = (arc4random() % RAND_MAX)));
 	else {
 		tmp = tree_eval(tree->lnode);
 		if (do_lint && (tmp->flags & (NUMCUR|NUMBER)) == 0)