linux_chromiumos_3_18: remove kernel due lack of maintainer/breakage

There is no maintainer for this package, probably not many users.
It requires effort to fix all third-party modules for this old kernel
versions. It might contain unpatched security holes.

For Pixel chromebooks, we have the samus-kernel.
Apart from that https://github.com/GalliumOS/linux might be a good choice.

pkgs/os-specific/linux/lttng-modules/default.nix

@@ -29,9 +29,7 @@ stdenv.mkDerivation rec {
     license = with licenses; [ lgpl21 gpl2 mit ];
     platforms = platforms.linux;
     maintainers = [ maintainers.bjornfor ];
-    broken =
-      (builtins.compareVersions kernel.version "3.18" == -1) ||
-      (kernel.features.chromiumos or false);
+    broken = builtins.compareVersions kernel.version "3.18" == -1;
   };
 
 }