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/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index 22b90df..3a9f236 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -1556,6 +1556,7 @@
   case UTT_IsFunction:              return "__is_function";
   case UTT_IsFundamental:           return "__is_fundamental";
   case UTT_IsIntegral:              return "__is_integral";
+  case UTT_IsInterfaceClass:        return "__is_interface_class";
   case UTT_IsLiteral:               return "__is_literal";
   case UTT_IsLvalueReference:       return "__is_lvalue_reference";
   case UTT_IsMemberFunctionPointer: return "__is_member_function_pointer";