Implement __has_virtual_destructor. Patch by Steven Watanabe.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112905 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index f1abd59..c4beab1 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -533,7 +533,7 @@
 ///                   '__has_trivial_copy'                    [TODO]
 ///                   '__has_trivial_constructor'
 ///                   '__has_trivial_destructor'
-///                   '__has_virtual_destructor'              [TODO]
+///                   '__has_virtual_destructor'
 ///                   '__is_abstract'                         [TODO]
 ///                   '__is_class'
 ///                   '__is_empty'                            [TODO]
@@ -903,6 +903,7 @@
   case tok::kw___has_nothrow_assign:
   case tok::kw___has_nothrow_copy:
   case tok::kw___has_nothrow_constructor:
+  case tok::kw___has_virtual_destructor:
     return ParseUnaryTypeTrait();
 
   case tok::at: {