don't run PyThread_exit_thread() when you don't have to

Code is from gh#python/cpython@83ad40e and it was released
upstream in 3.9.10.

Fixes: bsc#1203355
Patch: bpo-44434-libgcc_s-for-pthread_cancel.patch

Author: mcepl

Modules/_testcapimodule.c

@@ -3651,8 +3651,6 @@ temporary_c_thread(void *data)
     PyGILState_Release(state);
 
     PyThread_release_lock(test_c_thread->exit_event);
-
-    PyThread_exit_thread();
 }
 
 static PyObject *

Modules/_threadmodule.c

@@ -1027,7 +1027,10 @@ t_bootstrap(void *boot_raw)
     nb_threads--;
     PyThreadState_Clear(tstate);
     PyThreadState_DeleteCurrent();
-    PyThread_exit_thread();
+
+    // bpo-44434: Don't call explicitly PyThread_exit_thread(). On Linux with
+    // the glibc, pthread_exit() can abort the whole process if dlopen() fails
+    // to open the libgcc_s.so library (ex: EMFILE error).
 }
 
 static PyObject *