emacsPackages.ebuild-mode: switch to melpaBuild

Advantages:
- info manual is built and installed
- conform to package.el
  without any config, open a foo.ebuild file and its major-mode is set
  to ebuild-mode.

pkgs/applications/editors/emacs/elisp-packages/manual-packages/ebuild-mode/default.nix

@@ -1,6 +1,6 @@
-{ lib, trivialBuild, fetchurl }:
+{ lib, melpaBuild, fetchurl, writeText }:
 
-trivialBuild rec {
+melpaBuild rec {
   pname = "ebuild-mode";
   version = "1.65";
 
@@ -9,6 +9,14 @@ trivialBuild rec {
     sha256 = "sha256-vJ+UlPMIuZ02da9R67wIq2dVaWElu/sYmWx2KgBQ9B8=";
   };
 
+  commit = "not-used-but-has-to-be-set";
+
+  recipe = writeText "recipe" ''
+    (ebuild-mode
+      :url "https://anongit.gentoo.org/git/proj/ebuild-mode.git"
+      :fetcher git)
+  '';
+
   meta = with lib; {
     description = "Major modes for Gentoo package files";
     license = licenses.gpl2Plus;