Add support for builtin astype:
__builtin_astype(): Used to reinterpreted as another data type of the same size using for both scalar and vector data types.
Added test case.

llvm-svn: 132612
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 1206fe7..06c5645 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2770,6 +2770,7 @@
   case Expr::OpaqueValueExprClass:
   case Expr::PackExpansionExprClass:
   case Expr::SubstNonTypeTemplateParmPackExprClass:
+  case Expr::AsTypeExprClass:
     return ICEDiag(2, E->getLocStart());
 
   case Expr::SizeOfPackExprClass: