tmux: Update misc/tmux to 2.8

pkgsrc changes:
 - Address -Wint-conversion warnings and properly cast to long, patch by
   <christos> from NetBSD, thanks!
 - Remove patch-server-client.c, timersub() was added in compat.h
   since tmux-1.9 and is no longer needed
 - Take MAINTAINERship

Changes:
2.8
---
 * Make display-panes block the client until a pane is chosen or it
   times out.
 * Clear history on RIS like most other terminals do.
 * Add an "Any" key to run a command if a key is pressed that is not
   bound in the current key table.
 * Expand formats in load-buffer and save-buffer.
 * Add a rectangle_toggle format.
 * Add set-hook -R to run a hook immediately.
 * Add README.ja.
 * Add pane focus hooks.
 * Allow any punctuation as separator for s/x/y not only /.
 * Improve resizing with the mouse (fix resizing the wrong pane in some
   layouts, and allow resizing multiple panes at the same time).
 * Allow , and } to be escaped in formats as #, and #}.
 * Add KRB5CCNAME to update-environment.
 * Change meaning of -c to display-message so the client is used if it
   matches the session given to -t.
 * Fixes to : form of SGR.
 * Add x and X to choose-tree to kill sessions, windows or panes.


(leot)

$NetBSD: patch-tty-term.c,v 1.1 2018/10/21 21:22:47 leot Exp $

Address -Wint-conversion warnings and properly cast to long, from
NetBSD external/bsd/tmux/dist/tty-term.c patch by <christos>.

This was applied upstream via:

 <https://github.com/tmux/tmux/pull/1465>

--- tty-term.c.orig	2018-07-27 13:01:14.000000000 +0000
+++ tty-term.c
@@ -616,14 +616,14 @@ tty_term_string3(struct tty_term *term, 
 const char *
 tty_term_ptr1(struct tty_term *term, enum tty_code_code code, const void *a)
 {
-	return (tparm((char *) tty_term_string(term, code), a, 0, 0, 0, 0, 0, 0, 0, 0));
+	return (tparm((char *) tty_term_string(term, code), (long)a, 0, 0, 0, 0, 0, 0, 0, 0));
 }
 
 const char *
 tty_term_ptr2(struct tty_term *term, enum tty_code_code code, const void *a,
     const void *b)
 {
-	return (tparm((char *) tty_term_string(term, code), a, b, 0, 0, 0, 0, 0, 0, 0));
+	return (tparm((char *) tty_term_string(term, code), (long)a, (long)b, 0, 0, 0, 0, 0, 0, 0));
 }
 
 int