[Patch] Fix incorrect code page when setting console title on Win10

[宫大汉 via Cygwin-patches]

When Cygwin sets console titles on Win10 (has_con_24bit_colors && 
!con_is_legacy),
`WriteConsoleA` is used and causes an error if:
1. the environment variable of `LANG` is `***.UTF-8`
2. and the code page of console.exe is not UTF-8
  1. e.g. on my Computer, it's GB2312, for Chinese text


I've done some tests on msys2 and details are on 
https://github.com/git-for-windows/git/issues/2738,
and I filed a PR of https://github.com/git-for-windows/msys2-runtime/pull/25.
Then what should I do, in order to fix this on Cygwin?


The below is the commit's .patch file:


From 334f52a53a2e6b7f560b0e8810b9f672ebb3ad24 Mon Sep 17 00:00:00 2001
From: Dahan Gong <gdh1...@qq.com&gt;
Date: Fri, 31 Jul 2020 22:06:54 +0800
Subject: [PATCH] Fix incorrect code page in console title


`WriteConsoleA` always follows the current code page of a console window, so 
it's not suitable to pass a multi-byte string in `get_ttyp 
()-&gt;term_code_page` to it directly.


This PR turns to `WriteConsoleW` so that most characters will be translated "as 
is", and I've tested it on Win 10 v2004 (CMD: ver 10.0.19041.388).


Signed-off-by: gdh1995 <gdh1...@qq.com&gt;
---
&nbsp;winsup/cygwin/fhandler_console.cc | 18 +++++++++++++++++-
&nbsp;1 file changed, 17 insertions(+), 1 deletion(-)


diff --git a/winsup/cygwin/fhandler_console.cc 
b/winsup/cygwin/fhandler_console.cc
index dd979fb8e2..7870eeda81 100644
--- a/winsup/cygwin/fhandler_console.cc
+++ b/winsup/cygwin/fhandler_console.cc
@@ -80,6 +80,15 @@ static class write_pending_buffer
&nbsp; &nbsp;{
&nbsp; &nbsp; &nbsp;WriteConsoleA (handle, buf, ixput, wn, 0);
&nbsp; &nbsp;}
+&nbsp; inline char *c_str (size_t *psize = NULL)
+&nbsp; {
+&nbsp; &nbsp; size_t size = ixput < WPBUF_LEN ? ixput : WPBUF_LEN - 1;
+&nbsp; &nbsp; buf[size] = '\0';
+&nbsp; &nbsp; if (psize != NULL) {
+&nbsp; &nbsp; &nbsp; *psize = size;
+&nbsp; &nbsp; }
+&nbsp; &nbsp; return (char *) buf;
+&nbsp; }
&nbsp;} wpbuf;
&nbsp;
&nbsp;static void
@@ -3203,7 +3212,14 @@ fhandler_console::write (const void *vsrc, size_t len)
&nbsp;  &nbsp; &nbsp; if (*src < ' ')
&nbsp;  &nbsp; &nbsp; &nbsp; {
&nbsp;          if (wincap.has_con_24bit_colors () &amp;&amp; !con_is_legacy)
-               &nbsp; wpbuf.send (get_output_handle ());
+               &nbsp; {
+               &nbsp; &nbsp; size_t nms;
+               &nbsp; &nbsp; char *ms = wpbuf.c_str(&amp;nms);
+               &nbsp; &nbsp; wchar_t write_buf[TITLESIZE + 1];
+               &nbsp; &nbsp; DWORD done;
+               &nbsp; &nbsp; DWORD buf_len = sys_mbstowcs (write_buf, 
TITLESIZE, ms);
+               &nbsp; &nbsp; write_console (write_buf, buf_len, done);
+               &nbsp; }
&nbsp;          else if (*src == '\007' &amp;&amp; con.state == gettitle)
&nbsp;          &nbsp; set_console_title (con.my_title_buf);
&nbsp;          con.state = normal;