gh-111924: Use PyMutex for Runtime-global Locks. (gh-112207)

This replaces some usages of PyThread_type_lock with PyMutex, which does not require memory allocation to initialize.

This simplifies some of the runtime initialization and is also one step towards avoiding changing the default raw memory allocator during initialize/finalization, which can be non-thread-safe in some circumstances.

Python/pylifecycle.c

@@ -3056,13 +3056,13 @@ wait_for_thread_shutdown(PyThreadState *tstate)
 int Py_AtExit(void (*func)(void))
 {
     struct _atexit_runtime_state *state = &_PyRuntime.atexit;
-    PyThread_acquire_lock(state->mutex, WAIT_LOCK);
+    PyMutex_Lock(&state->mutex);
     if (state->ncallbacks >= NEXITFUNCS) {
-        PyThread_release_lock(state->mutex);
+        PyMutex_Unlock(&state->mutex);
         return -1;
     }
     state->callbacks[state->ncallbacks++] = func;
-    PyThread_release_lock(state->mutex);
+    PyMutex_Unlock(&state->mutex);
     return 0;
 }
 
@@ -3072,18 +3072,18 @@ call_ll_exitfuncs(_PyRuntimeState *runtime)
     atexit_callbackfunc exitfunc;
     struct _atexit_runtime_state *state = &runtime->atexit;
 
-    PyThread_acquire_lock(state->mutex, WAIT_LOCK);
+    PyMutex_Lock(&state->mutex);
     while (state->ncallbacks > 0) {
         /* pop last function from the list */
         state->ncallbacks--;
         exitfunc = state->callbacks[state->ncallbacks];
         state->callbacks[state->ncallbacks] = NULL;
 
-        PyThread_release_lock(state->mutex);
+        PyMutex_Unlock(&state->mutex);
         exitfunc();
-        PyThread_acquire_lock(state->mutex, WAIT_LOCK);
+        PyMutex_Lock(&state->mutex);
     }
-    PyThread_release_lock(state->mutex);
+    PyMutex_Unlock(&state->mutex);
 
     fflush(stdout);
     fflush(stderr);