sw doc model xml dump: recognize RES_TXTATR_META

Change-Id: I9283b8c9aa4bc87b3b65faf18258f590125aa6cc

sw/source/core/txtnode/txatbase.cxx

@@ -117,6 +117,11 @@ void SwTextAttr::dumpAsXml(xmlTextWriterPtr pWriter) const
             oValue = "rubytext: " + rFormat.GetText().toUtf8();
             break;
         }
+    case RES_TXTATR_META:
+        {
+            pWhich = "meta";
+            break;
+        }
     default:
         break;
     }