[newlib-cygwin] Cygwin: FIFO: add missing lock

[Ken Brown]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=4f25d82cb1f5f021a548bf6794dfe2f8767f2c0f

commit 4f25d82cb1f5f021a548bf6794dfe2f8767f2c0f
Author: Ken Brown <kbrown@cornell.edu>
Date:   Wed Jul 15 16:13:47 2020 -0400

    Cygwin: FIFO: add missing lock

Diff:
---
 winsup/cygwin/fhandler_fifo.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index 91a276ee9..b6e172ddc 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -422,7 +422,9 @@ fhandler_fifo::update_shared_handlers ()
   set_shared_nhandlers (nhandlers);
   memcpy (shared_fc_handler, fc_handler, nhandlers * sizeof (fc_handler[0]));
   shared_fc_handler_updated (true);
+  owner_lock ();
   set_prev_owner (me);
+  owner_unlock ();
   return 0;
 }