xtables: fix missing xtables_exit_error definition

iptables_exit_error is defined in iptables/iptables.c, that
symbol cannot be used by iptables/xtables.c

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/iptables/xtables.c b/iptables/xtables.c
index c0a6347..abc2379 100644
--- a/iptables/xtables.c
+++ b/iptables/xtables.c
@@ -114,13 +114,13 @@
 	{NULL},
 };
 
-void iptables_exit_error(enum xtables_exittype status, const char *msg, ...) __attribute__((noreturn, format(printf,2,3)));
+void xtables_exit_error(enum xtables_exittype status, const char *msg, ...) __attribute__((noreturn, format(printf,2,3)));
 
 struct xtables_globals xtables_globals = {
 	.option_offset = 0,
 	.program_version = IPTABLES_VERSION,
 	.orig_opts = original_opts,
-	.exit_err = iptables_exit_error,
+	.exit_err = xtables_exit_error,
 	.compat_rev = nft_compatible_revision,
 };
 
@@ -295,6 +295,26 @@
 	exit(0);
 }
 
+void
+xtables_exit_error(enum xtables_exittype status, const char *msg, ...)
+{
+	va_list args;
+
+	va_start(args, msg);
+	fprintf(stderr, "%s v%s: ", prog_name, prog_vers);
+	vfprintf(stderr, msg, args);
+	va_end(args);
+	fprintf(stderr, "\n");
+	if (status == PARAMETER_PROBLEM)
+		exit_tryhelp(status);
+	if (status == VERSION_PROBLEM)
+		fprintf(stderr,
+			"Perhaps iptables or your kernel needs to be upgraded.\n");
+	/* On error paths, make sure that we don't leak memory */
+	xtables_free_opts(1);
+	exit(status);
+}
+
 static void
 generic_opt_check(int command, int options)
 {