Add parser support for __builtin_stdarg_start, PR2531


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@53328 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 8b98cba..183d9a9 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -205,7 +205,8 @@
 
   if (BID == Builtin::BI__builtin_va_start ||
       BID == Builtin::BI__builtin_va_copy ||
-      BID == Builtin::BI__builtin_va_end)
+      BID == Builtin::BI__builtin_va_end ||
+      BID == Builtin::BI__builtin_stdarg_start)
     InitBuiltinVaListType();
     
   QualType R = Context.BuiltinInfo.GetBuiltinType(BID, Context);