gnu: Add libidn2.

* gnu/packages/libidn.scm (libidn2): New variable.

gnu/packages/libidn.scm

@@ -59,3 +59,25 @@ (define libidn-1.33
           (sha256
            (base32
             "068fjg2arlppjqqpzd714n1lf6gxkpac9v5yyvp1qwmv6nvam9s4")))))))
+
+(define-public libidn2
+  (package
+    (name "libidn2")
+    (version "0.11")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "ftp://alpha.gnu.org/gnu/libidn/libidn2-"
+                                  version ".tar.gz"))
+              (sha256
+               (base32
+                "1zxzhzx14q2b1xkx746pz4lawvqd8d055yy84n52ndwb4pf7nfax"))))
+    (build-system gnu-build-system)
+    (synopsis "Internationalized domain name library for IDNA2008")
+    (description "Libidn2 is an internationalized domain library implementing
+the IDNA2008 specifications.   Libidn2 is believed to be a complete IDNA2008
+implementation, but has yet to be as extensively used as the original Libidn
+library.")
+    (home-page "https://www.gnu.org/software/libidn/#libidn2")
+    ;; The command-line tool 'idn2' is GPL3+, while the library is dual-licensed
+    ;; GPL2+ or LGPL3+.
+    (license (list gpl2+ gpl3+ lgpl3+))))