project-lakitu: add cos-linux-mod class

Add cos-linux-mod class to encapsulate module building logic. Because
of different USE flags in kernel and module builds the toolchain
being used in both cases are slightly different. This can be fixed at
the module ebuild level but to avoid copy-pasting logic from one
ebuild to another - encapsulate it in a singe eclass that makes sure
kernel and modules are built the same way.

This still requires certain manual synchronization between cros-kernel2
and cos-linux-mod classes but it's more preferable to synchronize
single code unit instead of multiple.

BUG=b/186269275
TEST=presubmit
RELEASE_NOTE=None

Change-Id: Idf57d4b8397629d88b509871dbf3ca0bc4a35b38
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/16032
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-by: Roy Yang <royyang@google.com>
1 file changed