contrib: xcode3: select ARCHS to be built

(cherry picked from commit 49bbc50c)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

contrib/src/main.mak

@@ -128,6 +128,7 @@ endif
 
 XCODE_FLAGS = -sdk macosx$(OSX_VERSION)
 ifeq ($(shell xcodebuild -version 2>/dev/null | tee /dev/null|head -1|cut -d\  -f2|cut -d. -f1),3)
+XCODE_FLAGS += ARCHS=$(ARCH)
 # XCode 3 doesn't support -arch
 else
 XCODE_FLAGS += -arch $(ARCH)