gnu: bind: Rename variable to 'isc-bind'.

Reported by Leo Famulari.

* gnu/packages/dns.scm (bind): Rename to...
(isc-bind): ... this.
* gnu/packages/sssd.scm (sssd)[inputs]: Adjust accordingly.

gnu/packages/dns.scm

@@ -88,7 +88,9 @@ (define-public dnsmasq
     ;; Source files only say GPL2 and GPL3 are allowed.
     (license (list license:gpl2 license:gpl3))))
 
-(define-public bind
+;; 'bind' is the name of a built-in Guile procedure, which is why we choose a
+;; different name here.
+(define-public isc-bind
   (package
     (name "bind")
     (version "9.11.1")

gnu/packages/sssd.scm

@@ -131,7 +131,7 @@ (define-public sssd
              #t)))))
     (inputs
      `(("augeas" ,augeas)
-       ("bind" ,bind "utils")
+       ("bind" ,isc-bind "utils")
        ("c-ares" ,c-ares)
        ("curl" ,curl)
        ("cyrus-sasl" ,cyrus-sasl)