package/tmux: bump to version 2.9a

This is a bug fix release.
Changelog: https://raw.githubusercontent.com/tmux/tmux/2.9a/CHANGES

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/tmux/tmux.hash

@@ -1,3 +1,3 @@
 # Locally computed:
-sha256 34901232f486fd99f3a39e864575e658b5d49f43289ccc6ee57c365f2e2c2980  tmux-2.9.tar.gz
+sha256 839d167a4517a6bffa6b6074e89a9a8630547b2dea2086f1fad15af12ab23b25  tmux-2.9a.tar.gz
 sha256 ce75f1345a76c93bd0f413d1b93ff1baa0669f34a7242779a00c1b862b4f813a  COPYING

package/tmux/tmux.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-TMUX_VERSION = 2.9
+TMUX_VERSION = 2.9a
 TMUX_SITE = https://github.com/tmux/tmux/releases/download/$(TMUX_VERSION)
 TMUX_LICENSE = ISC
 TMUX_LICENSE_FILES = COPYING