update to use new linker option to re-export from libc++abi.dylb

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@117691 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/buildit b/lib/buildit
index feb14fb..737595f 100755
--- a/lib/buildit
+++ b/lib/buildit
@@ -49,11 +49,7 @@
 			-install_name /usr/lib/libc++.dylib \
 			${SDKROOT}/usr/lib/libc++abi.dylib \
 			-lSystem  \
-			-Xarch_x86_64 -exported_symbols_list \
-			-Xarch_x86_64 x86_64.exp \
-			-Xarch_i386 -exported_symbols_list \
-			-Xarch_i386 i386.exp \
-			-exported_symbols_list libc++abi.exp \
+			-Wl,-reexported_symbols_list,libc++abi.exp \
 			-Wl,-force_symbols_not_weak_list,notweak.exp"
 	fi
     ;;