Since all regrtest -j output is now done in the main thread we are no

longer using the print lock, so remove it.

Lib/test/regrtest.py

@@ -440,13 +440,12 @@ def accumulate_result(test, result):
                 resource_denieds.append(test)
 
     if use_mp:
-        from threading import Thread, Lock
+        from threading import Thread
         from queue import Queue, Empty
         from subprocess import Popen, PIPE, STDOUT
         from collections import deque
         # TextIOWrapper is not entirely thread-safe now,
         # it can produce duplicate output when printing from several threads.
-        print_lock = Lock()
         debug_output_pat = re.compile(r"\[\d+ refs\]$")
         pending = deque()
         output = Queue()