gnu: isc-dhcp: Update bundled BIND to 9.11.22 [security fixes].

Includes fixes for CVE-2020-8617, CVE-2020-8619, CVE-2020-8622,
CVE-2020-8623, and CVE-2020-8624.

* gnu/packages/admin.scm (isc-dhcp): Update bundled BIND to 9.11.22.

gnu/packages/admin.scm

 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2013 Cyril Roelandt <tipecaml@gmail.com>
-;;; Copyright © 2014, 2015, 2016, 2018, 2019 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2014, 2015, 2016, 2018, 2019, 2020 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2020 Eric Bavier <bavier@posteo.net>
 ;;; Copyright © 2015, 2016 Taylan Ulrich Bayırlı/Kammer <taylanbayirli@gmail.com>
 ;;; Copyright © 2015 Alex Sassmannshausen <alex.sassmannshausen@gmail.com>
@@ -946,7 +946,7 @@ (define-public alive
 (define-public isc-dhcp
   (let* ((bind-major-version "9")
          (bind-minor-version "11")
-         (bind-patch-version "18")
+         (bind-patch-version "22")
          (bind-release-type "")         ; for patch release, use "-P"
          (bind-release-version "")      ; for patch release, e.g. "6"
          (bind-version (string-append bind-major-version
@@ -1083,7 +1083,7 @@ (define-public isc-dhcp
                                         "/bind-" bind-version ".tar.gz"))
                     (sha256
                      (base32
-                      "0vws0zzb39mkphj4hhjrgfj9dzw951lc4pfa6pqg5ll5ma51mbsr"))))
+                      "1j9a4r83a77mp8k1y8z524c9rzdqgd8rzwczd6zwmw86a00xiimg"))))
 
                 ;; When cross-compiling, we need the cross Coreutils and sed.
                 ;; Otherwise just use those from %FINAL-INPUTS.