Add the Microsoft __is_interface_class type trait.
Patch by Andy Gibbs!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164591 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index 9b95641..37cdd14 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -1208,6 +1208,7 @@
   case tok::kw___is_class:
   case tok::kw___is_empty:
   case tok::kw___is_enum:
+  case tok::kw___is_interface_class:
   case tok::kw___is_literal:
   case tok::kw___is_arithmetic:
   case tok::kw___is_integral: