gcc spells it "warn_unused_result" (already supported) not "warnunusedresult"

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64849 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Parse/AttributeList.cpp

@@ -118,9 +118,6 @@ AttributeList::Kind AttributeList::getKind(const IdentifierInfo *Name) {
   case 15:
     if (!memcmp(Str, "ext_vector_type", 15)) return AT_ext_vector_type;
     break;
-  case 16:
-    if (!memcmp(Str, "warnunusedresult", 16)) return AT_warn_unused_result;
-    break;
   case 17:
     if (!memcmp(Str, "transparent_union", 17)) return AT_transparent_union;
     break;