Driver/Darwin: Switch to using -macosx for OS name in triples.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129834 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index d7959bd..02105ac 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -151,7 +151,7 @@
   
   llvm::SmallString<16> Str;
   llvm::raw_svector_ostream(Str)
-    << (isTargetIPhoneOS() ? "ios" : "osx")
+    << (isTargetIPhoneOS() ? "ios" : "macosx")
     << Version[0] << "." << Version[1] << "." << Version[2];
   Triple.setOSName(Str.str());