contrib: fixed libvpx compilation with Xcode 4.3 and later

contrib/src/vpx/libvpx-mac.patch

+libvpx's configure script hard-codes the SDK location of previous Xcode release in the /Developer folder. However, starting with Xcode 4.3, the SDKs moved to /Applications/Xcode.app/blabla
+VLC's contrib system is clever enough to detect this, but libvpx fails miserably. However, they are providing a work-around for iOS and Android, which is expanded by this patch.
+
+diff -ru libvpx/build/make/configure.sh libvpx/build/make/configure.sh
+--- libvpx/build/make/configure.sh	2012-06-08 10:26:47.000000000 +0200
++++ libvpx-fixed/build/make/configure.sh	2012-06-08 10:26:07.000000000 +0200
+@@ -628,6 +628,9 @@
+     if [ -d "/Developer/SDKs/MacOSX10.7.sdk" ]; then
+         osx_sdk_dir="/Developer/SDKs/MacOSX10.7.sdk"
+     fi
++    if [ -d "${sdk_path}" ]; then
++        osx_sdk_dir=${sdk_path}
++    fi
+ 
+     case ${toolchain} in
+         *-darwin8-*)

contrib/src/vpx/rules.mak

@@ -18,6 +18,9 @@ libvpx: libvpx-$(VPX_VERSION).tar.bz2 .sum-vpx
 	$(UNPACK)
 	$(APPLY) $(SRC)/vpx/libvpx-no-cross.patch
 	$(APPLY) $(SRC)/vpx/libvpx-no-abi.patch
+ifdef HAVE_MACOSX
+	$(APPLY) $(SRC)/vpx/libvpx-xcode43.patch
+endif
 	$(PATCH_BASH_LOCATION)
 	$(MOVE)
 
@@ -85,6 +88,12 @@ VPX_CONF := \
 ifndef HAVE_WIN32
 VPX_CONF += --enable-pic
 endif
+ifdef HAVE_MACOSX
+VPX_CONF += --sdk-path=$(MACOSX_SDK)
+endif
+ifdef HAVE_IOS
+VPX_CONF += --sdk-path=$(SDKROOT)
+endif
 
 .vpx: libvpx
 	cd $< && CROSS=$(VPX_CROSS) ./configure --target=$(VPX_TARGET) \