bitbake: bitbake-worker: Improve error handling

If bitbake-worker fails, return an error code showing that. Also
make the thread cleanup code explict in a finally clause as it would
otherwise hang.

[YOCTO #14393]

(Bitbake rev: 97541440e982848ef8bdbced22decdc24eda855b)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 7e0af70fb53fb13f824ca954b8cc1dffee730233)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-worker

@@ -505,9 +505,11 @@ except BaseException as e:
         import traceback
         sys.stderr.write(traceback.format_exc())
         sys.stderr.write(str(e))
+finally:
+    worker_thread_exit = True
+    worker_thread.join()
 
-worker_thread_exit = True
-worker_thread.join()
-
-workerlog_write("exitting")
+workerlog_write("exiting")
+if not normalexit:
+    sys.exit(1)
 sys.exit(0)