Improve Clang build fix and use it under Mac OS X as well. The problem

is specific to the verion of Clang (3.5 and newer) and not the platform.

This package now builds under Mac OS X Yosemite with the latest version
of Xcode tools.

multimedia/libvpx/Makefile

@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.51 2015/02/25 11:13:54 adam Exp $
+# $NetBSD: Makefile,v 1.52 2015/04/09 17:09:01 tron Exp $
 
 DISTNAME=	libvpx_1.3.0.orig
 PKGNAME=	${DISTNAME:S/_/-/:S/.orig//}
@@ -93,9 +93,12 @@ CONFIGURE_ARGS+=	--target=x86-solaris-gcc
 .include "../../mk/compiler.mk"
 .if !empty(PKGSRC_COMPILER:Mclang)
 CXXFLAGS+=	-std=c++11
-.  if ${OPSYS} == "NetBSD"
+.  if ${OPSYS} == "NetBSD" || ${OPSYS} == "Darwin"
 # https://bugzilla.mozilla.org/show_bug.cgi?id=982693
-CFLAGS+=	-fno-integrated-as
+SUBST_CLASSES+=		clang
+SUBST_STAGE.clang=	post-patch
+SUBST_FILES.clang=	build/make/Makefile
+SUBST_SED.clang=	-e 's/-DINLINE_ASM/-DINLINE_ASM -fno-integrated-as/'
 .  endif
 .endif