contrib: fix vorbis build on osx

gcc -O4 is apparently not recognized anymore

contrib/src/vorbis/osx.patch

+--- libvorbis/configure.ac.orig	2012-09-07 00:17:47.000000000 +0200
++++ libvorbis/configure.ac	2012-09-07 00:18:01.000000000 +0200
+@@ -199,8 +199,8 @@
+ 		PROFILE="-pg -g -O20 -D__NO_MATH_INLINES -fsigned-char $sparc_cpu" ;;
+ 	*-*-darwin*)
+ 		DEBUG="-DDARWIN -fno-common -force_cpusubtype_ALL -Wall -g -O0 -fsigned-char"
+-		CFLAGS="-DDARWIN -fno-common -force_cpusubtype_ALL -Wall -g -O4 -ffast-math -fsigned-char"
+-		PROFILE="-DDARWIN -fno-common -force_cpusubtype_ALL -Wall -g -pg -O4 -ffast-math -fsigned-char";;
++		CFLAGS="-DDARWIN -fno-common -force_cpusubtype_ALL -Wall -g -O3 -ffast-math -fsigned-char"
++		PROFILE="-DDARWIN -fno-common -force_cpusubtype_ALL -Wall -g -pg -O3 -ffast-math -fsigned-char";;
+ 	*-*-os2*)
+ 		# Use -W instead of -Wextra because gcc on OS/2 is an old version.
+ 		DEBUG="-g -Wall -W -D_REENTRANT -D__NO_MATH_INLINES -fsigned-char"

contrib/src/vorbis/rules.mak

@@ -25,12 +25,14 @@ $(TARBALLS)/libvorbis-$(VORBIS_VERSION).tar.xz:
 
 libvorbis: libvorbis-$(VORBIS_VERSION).tar.xz .sum-vorbis
 	$(UNPACK)
+	$(APPLY) $(SRC)/vorbis/osx.patch
 	$(UPDATE_AUTOCONFIG)
 	$(MOVE)
 
 DEPS_vorbis = ogg $(DEPS_ogg)
 
 .vorbis: libvorbis
+	$(RECONF) -Im4
 	cd $< && $(HOSTVARS) ./configure $(HOSTCONF) --disable-docs --disable-examples --disable-oggtest
 	cd $< && $(MAKE) install
 	touch $@