[newlib-cygwin/cygwin-3_6-branch] Cygwin: Note Ctrl-O (FLUSHO) fix to release note

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=822b49e97af9c6551911c0ff5297d31b61150e03

commit 822b49e97af9c6551911c0ff5297d31b61150e03
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Sat Aug 30 12:08:21 2025 +0900

    Cygwin: Note Ctrl-O (FLUSHO) fix to release note

Diff:
---
 winsup/cygwin/release/3.6.5 | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/winsup/cygwin/release/3.6.5 b/winsup/cygwin/release/3.6.5
index f14fbe6e1..6a37b6a43 100644
--- a/winsup/cygwin/release/3.6.5
+++ b/winsup/cygwin/release/3.6.5
@@ -22,3 +22,6 @@ Fixes:
 
 - Make process_fd correctly handle pty and console.
   Addresses: https://cygwin.com/pipermail/cygwin/2025-May/258167.html
+
+- Fix Ctrl-O (FLUSHO) handling.
+  Addresses: https://cygwin.com/pipermail/cygwin/2025-August/258717.html