Disable ThreadId check as the spec needs to be clarified first

See https://gitlab.com/sosy-lab/sv-comp/archives-2021/-/issues/30 for
discussion. Disabling the check for now discussed in SV-COMP Community
meeting held on 2020-12-01.

lint/witnesslint/linter.py

@@ -440,11 +440,15 @@ def handle_edge_data(self, data, key, parent):
                     break
             self.check_functionname(data.text, data.sourceline)
         elif key == witness.THREADID:
-            if data.text not in self.witness.threads:
-                logging.warning(
-                    "Thread with id {} doesn't exist".format(data.text),
-                    data.sourceline,
-                )
+            # Check disabled for SV-COMP'21 as questions about the specification
+            # need to be resolved first, see
+            # https://gitlab.com/sosy-lab/sv-comp/archives-2021/-/issues/30
+            # if data.text not in self.witness.threads:
+            #     logging.warning(
+            #         "Thread with id {} doesn't exist".format(data.text),
+            #         data.sourceline,
+            #     )
+            pass
         elif key == witness.CREATETHREAD:
             if data.text in self.witness.threads:
                 logging.warning(