installation of the compiler creates include/g++ if needed; mtree does not

need to do this.

src/etc/mtree/4.4BSD.dist

@@ -1,4 +1,4 @@
-#	$OpenBSD: 4.4BSD.dist,v 1.296 2017/04/17 21:45:34 deraadt Exp $
+#	$OpenBSD: 4.4BSD.dist,v 1.297 2017/04/18 15:15:09 deraadt Exp $
 
 /set type=dir uname=root gname=wheel mode=0755
 
@@ -133,8 +133,6 @@ usr
     include			gname=bin uname=root mode=0755
         arpa			gname=bin uname=root mode=0755
         ..
-        g++			gname=bin uname=root mode=0755
-        ..
         openssl			gname=bin uname=root mode=0755
         ..
         protocols		gname=bin uname=root mode=0755