bitbake: bitbake-worker: Ensure children have default sigterm handler

The children of the worker should have the default SIGTERM handler,
else they'll try and do cleanup which should only happen in the
parent leading to all kinds of bizarre build failures.

(Bitbake rev: a53c8d1f846d94082aa459996c4114f10970b8ef)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-worker

@@ -132,6 +132,8 @@ def fork_off_task(cfg, data, workerdata, fn, task, taskname, appends, taskdepdat
             global worker_pipe
             pipein.close()
 
+            signal.signal(signal.SIGTERM, signal.SIG_DFL)
+
             # Save out the PID so that the event can include it the
             # events
             bb.event.worker_pid = os.getpid()