lineage: Make mka a function again

* This caused breakages in subshells from scripts.

* Still keep the dropping of `-j`, as it's not needed.

This is a squashed revert of:

    Author:     Timi Rautamaki <timi.rautamaki@gmail.com>
    AuthorDate: 2022-03-24 08:21:34 +0000
    lineage: move mka definition above brunch

    Otherwise it's not defined for brunch.

    Change-Id: I642e3db365fab46d4428d1b1f310304280b72efc

    Author:     Alexander Koskovich <akoskovich@pm.me>
    AuthorDate: 2022-03-21 07:54:20 -0700

    envsetup: Remove threads argument from mka

     * "m" is multi-threaded by default.

    Change-Id: I5c9bb30dc49dafa31ba9fc70e617f477b6814b41

Change-Id: If4112ae739d8356f922cbbaf8e3d7ded5d078bd0