Don't build with -march=native on clang arches, ok ajacoutot@ (maintainer).

From my description,

> For gcc, lame has a big "experimental optimizer" section with
> -march=native and other flags that we don't want in bulk builds
> (but might be useful for self builds sometimes). It's controlled by
> --enable-expopt (the default is "none" to disable it),
>
> There is a similar section for clang which is just outside the "expopt"
> block. I think that's a mistake, but I don't want to poke around too much
> as they have other mistakes in their configure script nearby and I don't
> want to go down that rabbit hole ;)
>
> Here's a simple diff to neuter the check.

audio/lame/Makefile

@@ -1,10 +1,10 @@
-# $OpenBSD: Makefile,v 1.62 2018/06/27 17:25:50 sthen Exp $
+# $OpenBSD: Makefile,v 1.63 2018/10/04 14:48:38 sthen Exp $
 
 COMMENT=	lame ain't an MP3 encoder
 #'
 
 DISTNAME=	lame-3.100
-REVISION=	0
+REVISION=	1
 
 SHARED_LIBS +=  mp3lame              2.2      # 0.0
 

audio/lame/patches/patch-configure

@@ -0,0 +1,19 @@
+$OpenBSD: patch-configure,v 1.6 2018/10/04 14:48:38 sthen Exp $
+
+Disable adding -march=native on clang architectures. This allows use
+of instructions that are present on the build machine but not on other
+CPU types within the given architecture, so is not suitable for package
+builds.
+
+Index: configure
+--- configure.orig
++++ configure
+@@ -17563,7 +17563,7 @@ $as_echo "$as_me: WARNING: LAME doesn't know about you
+ 	esac
+ 
+ 
+-	if test "x${HAVE_CLANG}" = "xyes"; then
++	if false && test "x${HAVE_CLANG}" = "xyes"; then
+ 		case "${CLANG_VERSION}" in
+ 		3.89*|45.*)
+ 			OPTIMIZATION="-Ofast"