kernel: add CONFIG_CIFS_* like Fedora, Ubuntu

The plan is to fix mounting DFS shares on NixOS (for which some of these
options are needed), but I figured it might be a good idea to enable all
CONFIG_CIFS_* like Fedora 24 and Ubuntu 16.04 while at it. Ubuntu even
has CONFIG_CIFS_SMB311, but as Fedora do not, I left it out.

Mounting DFS shares still doesn't work; need to configure cifs.upcall
and /etc/request-key.conf. Until then, using GVFS as a workaround.

pkgs/os-specific/linux/kernel/common-config.nix

@@ -260,6 +260,11 @@ with stdenv.lib;
   CIFS_XATTR y
   CIFS_POSIX y
   CIFS_FSCACHE y
+  CIFS_STATS y
+  CIFS_WEAK_PW_HASH y
+  CIFS_UPCALL y
+  CIFS_ACL y
+  CIFS_DFS_UPCALL y
   CIFS_SMB2 y
   ${optionalString (versionAtLeast version "3.12") ''
     CEPH_FSCACHE y