bpo-39984: Pass tstate to _PyEval_SignalAsyncExc() (GH-19049)

_PyEval_SignalAsyncExc() and _PyEval_FiniThreads() now expect tstate,
instead of ceval.
diff --git a/Python/ceval_gil.h b/Python/ceval_gil.h
index f8b06ac..3e9f405 100644
--- a/Python/ceval_gil.h
+++ b/Python/ceval_gil.h
@@ -286,7 +286,7 @@
 
     /* Don't access tstate if the thread must exit */
     if (!must_exit && tstate->async_exc != NULL) {
-        _PyEval_SignalAsyncExc(ceval);
+        _PyEval_SignalAsyncExc(tstate);
     }
 
     MUTEX_UNLOCK(gil->mutex);