[3.12] GH-110455: Guard assert(tstate->thread_id > 0) with GH-ifndef HAVE_PTHREAD_STUBS (GH-110487) (GH-110491)

GH-110455: Guard `assert(tstate->thread_id > 0)` with `GH-ifndef HAVE_PTHREAD_STUBS` (GH-110487)
(cherry picked from commit 5fd8821)

Co-authored-by: Brett Cannon <[email protected]>

Author: miss-islington

Misc/NEWS.d/next/Core and Builtins/2023-10-06-12-00-43.gh-issue-110455.8BjNGg.rst

@@ -0,0 +1,3 @@
+Guard ``assert(tstate->thread_id > 0)`` with ``#ifndef HAVE_PTHREAD_STUBS``.
+This allows for for pydebug builds to work under WASI which (currently)
+lacks thread support.

Python/pystate.c

@@ -264,10 +264,10 @@ static void
 unbind_tstate(PyThreadState *tstate)
 {
     assert(tstate != NULL);
-    // XXX assert(tstate_is_alive(tstate));
     assert(tstate_is_bound(tstate));
-    // XXX assert(!tstate->_status.active);
+#ifndef HAVE_PTHREAD_STUBS
     assert(tstate->thread_id > 0);
+#endif
 #ifdef PY_HAVE_THREAD_NATIVE_ID
     assert(tstate->native_thread_id > 0);
 #endif