gnu: ubridge: Don't use unstable tarball.

* gnu/packages/networking.scm (ubridge)[source]: Use GIT-FETCH and
GIT-FILE-NAME.

gnu/packages/networking.scm

@@ -2218,21 +2218,22 @@ SNMP v3 using both IPv4 and IPv6.")
   (package
     (name "ubridge")
     (version "0.9.15")
-    (source (origin
-              (method url-fetch)
-              (uri (string-append "https://github.com/GNS3/ubridge/archive/v"
-                                  version ".tar.gz"))
-              (file-name (string-append name "-" version ".tar.gz"))
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/GNS3/ubridge.git")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
        (sha256
-               (base32
-                "0nmj37s7wvl7c36qbdv33rk9fyniwfk73qwb61ingni5siw67mr3"))))
+        (base32 "0fl07zyall04map6v2l1bclqh8y3rrhsx61s2v0sr8b00j201jg4"))))
     (build-system gnu-build-system)
     (arguments
      `(#:tests? #f                      ; no tests
        #:make-flags '("CC=gcc")
        #:phases
        (modify-phases %standard-phases
-         (delete 'configure)
+         (delete 'configure)            ; no configure script
          (add-before 'install 'set-bindir
            (lambda* (#:key  inputs outputs #:allow-other-keys)
              (let ((bin (string-append (assoc-ref outputs "out")