gnu: whois: Update to 5.2.19.

* gnu/packages/networking.scm (whois): Update to 5.2.19.
[arguments]: Don't set HAVE_LIBIDN in 'setenv' phase; this is now autodetected.
[native-inputs]: Add PKG-CONFIG.

gnu/packages/networking.scm

@@ -450,7 +450,7 @@ (define-public iodine
 (define-public whois
   (package
     (name "whois")
-    (version "5.2.18")
+    (version "5.2.19")
     (source
      (origin
        (method url-fetch)
@@ -458,7 +458,7 @@ (define-public whois
                            name "_" version ".tar.xz"))
        (sha256
         (base32
-         "1mcpgj18n1xppvlhjqzpj05yr5z48bym9bd88k10fwgkmwk0spf3"))))
+         "0b16w48c17k35lhd95qcl2kjq2rahk8znkg3w467rf3kzmsa4fbc"))))
     (build-system gnu-build-system)
     ;; TODO: unbundle mkpasswd binary + its po files.
     (arguments
@@ -471,13 +471,14 @@ (define-public whois
          (add-before 'build 'setenv
            (lambda _
              (setenv "HAVE_ICONV" "1")
-             (setenv "HAVE_LIBIDN" "1")
              #t)))))
     (inputs
+     ;; TODO: Switch to libidn2 when >= 2.0.3 is ungrafted in master.
      `(("libidn" ,libidn)))
     (native-inputs
      `(("gettext" ,gettext-minimal)
-       ("perl" ,perl)))
+       ("perl" ,perl)
+       ("pkg-config" ,pkg-config)))
     (synopsis "Improved whois client")
     (description "This whois client is intelligent and can
 automatically select the appropriate whois server for most queries.