lkft: Add 4.18 stable, update all stable kernel, config fragment too

[mrchapp]

Three things in three commits:

• add 4.18 stable kernel,
• update all stable kernels to use lkft config fragment, and
• update 4.4 lkft config fragment to include autogroup config.

[mrchapp]

Updated. Is 4.18 looking better now?

[roxell]

looks good