Synchronize on NetBSD-CVS (2013/12/1 12:00:00 UTC)

- Fix for possible unset uid/gid in toproto
 - Fix for default mtree style
 - Update libelf
 - Importing libexecinfo
 - Resynchronize GCC, mpc, gmp, mpfr
 - build.sh: Replace params with show-params.
     This has been done as the make target has been renamed in the same
     way, while a new target named params has been added. This new
     target generates a file containing all the parameters, instead of
     printing it on the console.
 - Update test48 with new etc/services (Fix by Ben Gras <ben@minix3.org)
     get getservbyport() out of the inner loop

Change-Id: Ie6ad5226fa2621ff9f0dee8782ea48f9443d2091

common/lib/libc/string/consttime_memequal.c

@@ -0,0 +1,32 @@
+/* $NetBSD: consttime_memequal.c,v 1.4 2013/08/28 19:31:14 riastradh Exp $ */
+
+#if !defined(_KERNEL) && !defined(_STANDALONE)
+#include "namespace.h"
+#include <string.h>
+#ifdef __weak_alias
+__weak_alias(consttime_memequal,_consttime_memequal)
+#endif
+#else
+#include <lib/libkern/libkern.h>
+#endif
+
+int
+consttime_memequal(const void *b1, const void *b2, size_t len)
+{
+	const char *c1 = b1, *c2 = b2;
+	int res = 0;
+
+	while (len --)
+		res |= *c1++ ^ *c2++;
+
+	/*
+	 * If the compiler for your favourite architecture generates a
+	 * conditional branch for `!res', it will be a data-dependent
+	 * branch, in which case this should be replaced by
+	 *
+	 *	return (1 - (1 & ((res - 1) >> 8)));
+	 *
+	 * or rewritten in assembly.
+	 */
+	return !res;
+}