Provide half floating point support as a storage only type.
Lack of half FP was a regression compared to llvm-gcc.

llvm-svn: 142016
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index ab5c8cf..3db75ba 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -1374,6 +1374,7 @@
   case BuiltinType::Long : return Importer.getToContext().LongTy;
   case BuiltinType::LongLong : return Importer.getToContext().LongLongTy;
   case BuiltinType::Int128 : return Importer.getToContext().Int128Ty;
+  case BuiltinType::Half: return Importer.getToContext().HalfTy;
   case BuiltinType::Float: return Importer.getToContext().FloatTy;
   case BuiltinType::Double: return Importer.getToContext().DoubleTy;
   case BuiltinType::LongDouble: return Importer.getToContext().LongDoubleTy;