chromium: use jumbo builds to speedup compilation

On Hetzner machine with 1 core: 4h40m
On Hetzner machine with 8 cores: 1h20m

pkgs/applications/networking/browsers/chromium/common.nix

@@ -222,6 +222,8 @@ let
       use_gold = true;
       gold_path = "${stdenv.cc}/bin";
       is_debug = false;
+      # at least 2X compilation speedup
+      use_jumbo_build = true;
 
       proprietary_codecs = false;
       use_sysroot = false;