Use VersionTuple to manage macosx versions in the driver. No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@152504 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index a457223..1eb7c9c 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -182,14 +182,10 @@
   if (!isTargetInitialized())
     return Triple.getTriple();
 
-  unsigned Version[3];
-  getTargetVersion(Version);
-
   SmallString<16> Str;
-  llvm::raw_svector_ostream(Str)
-    << (isTargetIPhoneOS() ? "ios" : "macosx")
-    << Version[0] << "." << Version[1] << "." << Version[2];
-  Triple.setOSName(Str.str());
+  Str += isTargetIPhoneOS() ? "ios" : "macosx";
+  Str += getTargetVersion().getAsString();
+  Triple.setOSName(Str);
 
   return Triple.getTriple();
 }