mp3gain: Add package

This adds mp3gain which is a normalizer for mp3 audio files.

pkgs/applications/audio/mp3gain/default.nix

@@ -0,0 +1,28 @@
+{ stdenv, fetchurl, unzip }:
+
+stdenv.mkDerivation {
+  name = "mp3gain-1.5.2";
+  src = fetchurl {
+    url = "http://downloads.sourceforge.net/mp3gain/mp3gain-1_5_2-src.zip";
+    sha256 = "1jkgry59m8cnnfq05b9y1h4x4wpy3iq8j68slb9qffwa3ajcgbfv";
+  };
+
+  buildInputs = [ unzip ];
+
+  sourceRoot = ".";
+
+  buildFlags = [ "OSTYPE=linux" ];
+
+  installPhase = ''
+    mkdir -p $out/usr/bin
+    cp mp3gain $out/usr/bin
+  '';
+
+  meta = {
+    description = "Lossless mp3 normalizer with statistical analysis";
+    homepage = http://mp3gain.sourceforge.net/;
+    license = stdenv.lib.licenses.lgpl21;
+    platforms = stdenv.lib.platforms.linux;
+    maintainers = [ stdenv.lib.maintainers.devhell ];
+  };
+}

pkgs/top-level/all-packages.nix

@@ -10288,6 +10288,8 @@ let
     inherit (gnome3) gnome_icon_theme;
   };
 
+  mp3gain = callPackage ../applications/audio/mp3gain { };
+
   mp3info = callPackage ../applications/audio/mp3info { };
 
   mp3splt = callPackage ../applications/audio/mp3splt { };