kernel: Add version 4.1 latest

pkgs/os-specific/linux/kernel/linux-4.1.nix

···
+{ stdenv, fetchurl, ... } @ args:
+
+import ./generic.nix (args // rec {
+  version = "4.1";
+  modDirVersion = "4.1.0";
+  extraMeta.branch = "4.1";
+
+  src = fetchurl {
+    url = "mirror://kernel/linux/kernel/v4.x/linux-${version}.tar.xz";
+    sha256 = "17rdly75zh49m6r32yy03xappl7ajcqbznq09pm1q7mcb841zxfa";
+  };
+
+  features.iwlwifi = true;
+  features.efiBootStub = true;
+  features.needsCifsUtils = true;
+  features.canDisableNetfilterConntrackHelpers = true;
+  features.netfilterRPFilter = true;
+} // (args.argsOverride or {}))

pkgs/top-level/all-packages.nix

···
       ];
   };
 
+  linux_4_1 = makeOverridable (import ../os-specific/linux/kernel/linux-4.1.nix) {
+    inherit fetchurl stdenv perl buildLinux;
+    kernelPatches = [ kernelPatches.bridge_stp_helper ]
+      ++ lib.optionals ((platform.kernelArch or null) == "mips")
+      [ kernelPatches.mips_fpureg_emu
+        kernelPatches.mips_fpu_sigill
+        kernelPatches.mips_ext3_n32
+      ];
+  };
+
   linux_testing = makeOverridable (import ../os-specific/linux/kernel/linux-testing.nix) {
     inherit fetchurl stdenv perl buildLinux;
     kernelPatches = [ kernelPatches.bridge_stp_helper ]
···
   linux = linuxPackages.kernel;
 
   # Update this when adding the newest kernel major version!
-  linuxPackages_latest = pkgs.linuxPackages_4_0;
+  linuxPackages_latest = pkgs.linuxPackages_4_1;
   linux_latest = linuxPackages_latest.kernel;
 
   # Build the kernel modules for the some of the kernels.
···
   linuxPackages_3_18 = recurseIntoAttrs (linuxPackagesFor pkgs.linux_3_18 linuxPackages_3_18);
   linuxPackages_3_19 = recurseIntoAttrs (linuxPackagesFor pkgs.linux_3_19 linuxPackages_3_19);
   linuxPackages_4_0 = recurseIntoAttrs (linuxPackagesFor pkgs.linux_4_0 linuxPackages_4_0);
+  linuxPackages_4_1 = recurseIntoAttrs (linuxPackagesFor pkgs.linux_4_1 linuxPackages_4_1);
   linuxPackages_testing = recurseIntoAttrs (linuxPackagesFor pkgs.linux_testing linuxPackages_testing);
   linuxPackages_custom = {version, src, configfile}:
                            let linuxPackages_self = (linuxPackagesFor (pkgs.linuxManualConfig {inherit version src configfile;