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

[Ken Brown]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bf07202e16f3b058e78d8afe74878cd828125e8a

commit bf07202e16f3b058e78d8afe74878cd828125e8a
Author: Ken Brown <kbrown@cornell.edu>
Date:   Tue May 19 10:25:43 2020 -0400

    Cygwin: FIFO: add missing unlock
    
    There was a missing call to reader_opening_unlock on one of the error
    exits in fhandler_fifo::open.

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

diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index ab4b93942..3d34cdfab 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -1020,6 +1020,7 @@ err_close_reader:
   saved_errno = get_errno ();
   close ();
   set_errno (saved_errno);
+  reader_opening_unlock ();
   return 0;
 err_close_cancel_evt:
   NtClose (cancel_evt);