mouse clicks don't work on ncurses-6.2, generate garbage to stdout

[slyfox]

It's forward of downstream ​https://bugs.gentoo.org/753578 report.

When mc is built with ncurses-6.2 mouse keypresses in xterm don't work and generate garbage output. The following workaround seems to be enough to fix it locally:

lib/tty/key.c

@@ -2124 +2124 @@
         gboolean extended = c == MCKEY_EXTENDED_MOUSE;
 
 #ifdef KEY_MOUSE
-        extended = extended || (c == KEY_MOUSE && xmouse_seq == NULL
-                                && xmouse_extended_seq != NULL);
+        extended = extended || (c == KEY_MOUSE && xmouse_extended_seq != NULL);
 #endif /* KEY_MOUSE */
 
         xmouse_get_event (event, extended);

$ LANG=C ./src/mc --version
GNU Midnight Commander 4.8.25-59-ga2bccac62
Built with GLib 2.64.5
Built with ncursesw 6.2
With builtin Editor
With subshell support as default
With support for background operations
With mouse support on xterm
With support for X11 events
With internationalization support
With multiple codepages support
With ext2fs attributes support
Virtual File Systems:
 cpiofs, tarfs, sfs, extfs, ftpfs, sftpfs, fish
Data types:
 char: 8; int: 32; long: 64; void *: 64; size_t: 64; off_t: 64;

Some details:

$ tput kmous | cat -v
^[[M
$ echo $TERM
xterm-256color

Actual generated sequences by xterm are in form of "\e[<0;10;28M", but mc expects-non-extended form of "\e[bxy".