Don't reify a JIT frame when there is no thread state

Summary:
On D115743871 when I ran the AI Labs test `apf_perf_cogwheel_mtml_ig_fm_multihost_train` I was hitting an error in all the runs with the JIT enabled.

AI Labs Run: https://www.internalfb.com/family_of_labs/test_results/175921865618156?test_name=ai_lab.APF.apf_perf_cogwheel_mtml_ig_fm_multihost_train
Treatment #1 MAST job logs [link](https://www.internalfb.com/mlhub/pipelines/runs/mast/aps-cogwheel_aps_multihost_ig_fm_v4-a3ec2e8726?job_attempt=2&version=0&tab=logs)

**Relevant Stack Trace (condensed)**
```
PyErr_GetRaisedException          ← faults here
_PyFrame_ReifyFrame
PyUnstable_InterpreterFrame_GetLine
(unknown) ×2                      ← profiler's stack walker, unsymbolized
──── libc_sigaction ────
epoll_wait
select_epoll_poll                 ← inside Py_BEGIN_ALLOW_THREADS
cinderx::jit::rt::call  ×2        ← JIT frames
```

It seems like this happened when strobelight was trying to get the line number of a jit frame and the frame was being reified. Because the GIL was released it wasn't possible to do a local thread state get in `_PyFrame_ReifyFrame()`. The fix here is to not reify the frame if there is no thread state.

Reviewed By: DinoV

Differential Revision: D116513961

fbshipit-source-id: efb877259d5342c9cfc05958e4076064ed0b728c

Author: Subbarao Garlapati

Python/frame.c

@@ -149,6 +149,12 @@ _PyFrame_ClearExceptCode(_PyInterpreterFrame *frame)
 int
 _PyFrame_InitializeExternalFrame(_PyInterpreterFrame *frame)
 {
+    // Profilers can reach this from a signal handler on a thread that has
+    // released the GIL, where there's no thread state to reify with.
+    if (PyThreadState_GetUnchecked() == NULL) {
+        return 0;
+    }
+
     PyObject *executor = PyStackRef_AsPyObjectBorrow(frame->f_executable);
     if (PyUnstable_JITExecutable_Check(executor)) {
         PyUnstable_PyJitExecutable *jit_exec = (PyUnstable_PyJitExecutable *)executor;