NetBSD re-synchronization of the source tree

This brings our tree to NetBSD 7.0, as found on -current on the
10-10-2015.

This updates:
 - LLVM to 3.6.1
 - GCC to GCC 5.1
 - Replace minix/commands/zdump with usr.bin/zdump
 - external/bsd/libelf has moved to /external/bsd/elftoolchain/
 - Import ctwm
 - Drop sprintf from libminc

Change-Id: I149836ac18e9326be9353958bab9b266efb056f0

include/string.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: string.h,v 1.48 2013/08/28 17:47:07 riastradh Exp $	*/
+/*	$NetBSD: string.h,v 1.49 2014/09/24 18:16:36 christos Exp $	*/
 
 /*-
  * Copyright (c) 1990, 1993
@@ -102,6 +102,7 @@ size_t	 strlcpy(char *, const char *, size_t);
 char	*strsep(char **, const char *);
 char	*stresep(char **, const char *, int);
 char	*strndup(const char *, size_t);
+char	*strnstr(const char *, const char *, size_t);
 void	*memrchr(const void *, int, size_t);
 void	*explicit_memset(void *, int, size_t);
 int	consttime_memequal(const void *, const void *, size_t);