Doc nits for bpo-16500 (#1841)

* Doc nits for bpo-16500

* Fix more references

Python/ceval.c

@@ -232,10 +232,10 @@ PyEval_ReleaseThread(PyThreadState *tstate)
     drop_gil(tstate);
 }
 
-/* This function is called from PyOS_AfterFork to destroy all threads which are
- * not running in the child process, and clear internal locks which might be
- * held by those threads. (This could also be done using pthread_atfork
- * mechanism, at least for the pthreads implementation.) */
+/* This function is called from PyOS_AfterFork_Child to destroy all threads
+ * which are not running in the child process, and clear internal locks
+ * which might be held by those threads.
+ */
 
 void
 PyEval_ReInitThreads(void)

Python/import.c

@@ -194,7 +194,7 @@ _PyImport_ReleaseLock(void)
     return 1;
 }
 
-/* This function is called from PyOS_AfterFork to ensure that newly
+/* This function is called from PyOS_AfterFork_Child to ensure that newly
    created child processes do not share locks with the parent.
    We now acquire the import lock around fork() calls but on some platforms
    (Solaris 9 and earlier? see isue7242) that still left us with problems. */

Python/pystate.c

@@ -800,7 +800,7 @@ _PyGILState_Fini(void)
     autoInterpreterState = NULL;
 }
 
-/* Reset the TLS key - called by PyOS_AfterFork().
+/* Reset the TLS key - called by PyOS_AfterFork_Child().
  * This should not be necessary, but some - buggy - pthread implementations
  * don't reset TLS upon fork(), see issue #10517.
  */

Python/thread.c

@@ -325,7 +325,7 @@ PyThread_delete_key_value(int key)
 }
 
 /* Forget everything not associated with the current thread id.
- * This function is called from PyOS_AfterFork().  It is necessary
+ * This function is called from PyOS_AfterFork_Child().  It is necessary
  * because other thread ids which were in use at the time of the fork
  * may be reused for new threads created in the forked process.
  */