nixpkgs: git - link git-http-backend into $PATH

This makes it easier for tools (like Phabricator) to find
git-http-backend to enable HTTP(S) transport support.

Signed-off-by: Austin Seipp <[e-mail]>

pkgs/applications/version-management/git-and-tools/git/default.nix

···
       # gitweb.cgi, need to patch so that it's found
       sed -i -e "s|'compressor' => \['gzip'|'compressor' => ['${gzip}/bin/gzip'|" \
           $out/share/gitweb/gitweb.cgi
+
+      # Also put git-http-backend into $PATH, so that we can use smart
+      # HTTP(s) transports for pushing
+      ln -s $out/libexec/git-core/git-http-backend $out/bin/git-http-backend
     ''
 
    + (if svnSupport then