irssi: security bump to 0.8.21

Bugfixes:

- CVE-2017-5193: Correct a NULL pointer dereference in the nickcmp function
  found by Joseph Bisch (GL#1)

- CVE-2017-5194: Correct an error when receiving invalid nick message (GL#4,
  #466)

- CVE-2017-5195: Correct an out of bounds read in certain incomplete control
  codes found by Joseph Bisch (GL#2)

- CVE-2017-5196: Correct an out of bounds read in certain incomplete
  character sequences found by Hanno Böck and independently by J.  Bisch
  (GL#3)

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/irssi/irssi.hash

@@ -1,2 +1,2 @@
 # Locally calculated after checking pgp signature
-sha256	7882c4e821f5aac469c5e69e69d7e235f4986101285c675e81a9a95bfb20505a	irssi-0.8.20.tar.xz
+sha256	e433063b8714dcf17438126902c9a9d5c97944b3185ecd0fc5ae25c4959bf35a	irssi-0.8.21.tar.xz

package/irssi/irssi.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-IRSSI_VERSION = 0.8.20
+IRSSI_VERSION = 0.8.21
 IRSSI_SOURCE = irssi-$(IRSSI_VERSION).tar.xz
 # Do not use the github helper here. The generated tarball is *NOT* the
 # same as the one uploaded by upstream for the release.