build: Add Lineage build support

Squashed also with the following changes:

  Author: Luca Stefani <luca020400@lineageos.org>
  Date:   Thu Aug 17 22:22:13 2017 +0200

    core: Include Lineage pathmap

  Change-Id: Ie25dee383cc5bc9bb6390cff2cb2460d526d80b6

  Author: Simon Shields <simon@lineageos.org>
  Date:   Fri Mar 2 12:55:47 2018 +1100

    build: unconditionally use lineage pathmap

    even if we're not building a lineage target, we need to
    use the lineage pathmap to make things like recovery and ril
    happy

  Change-Id: I974c30ad10d4ff5b7805c3df9c22010f1e002bf1

  Author: Luca Stefani <luca.stefani.ge1@gmail.com>
  Date:   Tue Jan 22 15:50:52 2019 +0100

    Don't export BUILD_NUMBER in envsetup

    * The value is meant to be set only before running an /official/ build
    * This allows us to execute consecutive make commands without
      running kati for every invocation

  Change-Id: Ifa94b839f30c7260009c8a3c91c202b50e28022e

  Author: Luca Stefani <luca020400@lineageos.org>
  Date:   Fri Aug 18 10:17:00 2017 +0200

    envsetup: Call fixup_common_out_dir

  Change-Id: I84e16b0df5822cfd8514c46d709109a13c20f86e

Change-Id: Iab8b2ef8b644a7bea10bfd28b99d9e69539b1357