Added the kernel signed packages into 'debian_pkg_dirs_sign',
then these packages can be discovered and built by build-pkgs.
This causes the new build type 'sign' created and it has the
lowest priority which make sure that the signed packages should
be built in the last batch in 'distro' layer.
The reason for adding build type 'sign' is also described in the
related commit [Add build type sign and set the priority in distro]
in starlingx/tools,
from https://review.opendev.org/c/starlingx/tools/+/842663
Test Plan:
Pass: build-pkgs -a
Pass: build-pkgs -a -l <layer>
Pass: Make sure linux and linux-rt has been built
Run the script to sign the kernel
build-pkgs -b sign -p kernel-std-signed, kernel-rt-signed
Depends-On: https://review.opendev.org/c/starlingx/tools/+/842663
Story: 2009221
Task: 45383
Signed-off-by: Haiqing Bai <haiqing.bai@windriver.com>
Change-Id: I4de8c632e2e17d1111e4bce1e246d924be65c373
21e774d0ae