Implement enough of the 'auto' keyword so we can claim to support N2546.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74307 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 8a0ad08..b584142 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -245,6 +245,11 @@
     Result = Context.getDecltypeType(E);
     break;
   }
+  case DeclSpec::TST_auto: {
+    // TypeQuals handled by caller.
+    Result = Context.UndeducedAutoTy;
+    break;
+  }
     
   case DeclSpec::TST_error:
     Result = Context.IntTy;