qtox: drop gtk2 dependency

Tray icon still works without gtk2.

pkgs/applications/networking/instant-messengers/qtox/default.nix

···
   libtoxcore,
   libpthreadstubs, libXdmcp, libXScrnSaver,
   qtbase, qtsvg, qttools, qttranslations,
-  atk, cairo, ffmpeg, filter-audio, gdk_pixbuf, glib, gtk2, libsodium, libopus,
-  libvpx, openal, opencv, pango, pcre, qrencode, sqlcipher }:
+  ffmpeg, filter-audio, libsodium, libopus,
+  libvpx, openal, opencv, pcre, qrencode, sqlcipher }:
 
 mkDerivation rec {
   name = "qtox-${version}";
···
     libtoxcore
     libpthreadstubs libXdmcp libXScrnSaver
     qtbase qtsvg qttools qttranslations
-    atk cairo ffmpeg filter-audio gdk_pixbuf glib gtk2 libopus libsodium
-    libvpx openal opencv pango pcre qrencode sqlcipher
+    ffmpeg filter-audio libopus libsodium
+    libvpx openal opencv pcre qrencode sqlcipher
   ];
 
   nativeBuildInputs = [ cmake pkgconfig ];
 
+  enableParallelBuilding = true;
+
   cmakeFlags = [
     "-DGIT_DESCRIBE=${version}"
+    "-DENABLE_STATUSNOTIFIER=False"
+    "-DENABLE_GTK_SYSTRAY=False"
+    "-DENABLE_APPINDICATOR=False"
   ];
 
-  installPhase = ''
-    runHook preInstall
-
-    install -Dm755 qtox $out/bin/qtox
-
-    runHook postInstall
-  '';
-
   meta = with lib; {
     description = "Qt Tox client";
-    license = licenses.gpl3;
+    license     = licenses.gpl3;
     maintainers = with maintainers; [ viric jgeerds akaWolf peterhoeg ];
-    platforms = platforms.all;
+    platforms   = platforms.all;
   };
 }