ports/187018: [patch] multimedia/gstreamer-ffmpeg fails during configure with clang 3.4

[Don Lewis]

This is probably a better patch:

Index: Makefile
===================================================================
--- Makefile	(revision 345674)
+++ Makefile	(working copy)
@@ -22,7 +22,7 @@
 
 LIBAV_VERSION=	0.7.7
 WRKSRC=		${WRKDIR}/gst-ffmpeg-${PORTVERSION}
-USES=		gmake pkgconfig
+USES=		gmake pkgconfig compiler:features
 USE_LDCONFIG=	yes
 USE_GSTREAMER=	yes
 GNU_CONFIGURE=	yes
@@ -30,7 +30,6 @@
 		--enable-runtime-cpudetect \
 		--enable-pic
 LDFLAGS+=	-Wl,-Bsymbolic
-CFLAGS+=	-fno-force-addr
 CONFIGURE_ENV=	PKG_CONFIG=${PKG_CONFIG}
 
 PLIST_SUB=	VERSION="${GST_VERSION}"
@@ -67,6 +66,10 @@
 
 .endif
 
+.if ${COMPILER_TYPE} == "gcc"
+CFLAGS+=	-fno-force-addr
+.endif
+
 post-patch:
 	@${MV} ${WRKSRC}/gst-libs/ext/libav ${WRKSRC}/gst-libs/ext/libav.old
 	@${MV} ${WRKDIR}/libav-${LIBAV_VERSION} ${WRKSRC}/gst-libs/ext/libav