Add support for s390 architecture for linuxkit/alpine and the
other docker images in tools and pkg.
Signed-off-by: Alice Frosi <alice@linux.vnet.ibm.com>
Alpine is the base docker image for the LinuxKit, but currently
it only supports amd64 architecture. This patch is try to unify
the alpine tool docker image build process order to suport other
architectures, such as AArch64, by using '--build-arg' to override
the alpine base image specified by 'FROM' in the Dockerfile.
Also this patch splits the standalone packages into 2 parts:
one is common for all archs, another is arch-specific.
Signed-off-by: Dennis Chen <dennis.chen@arm.com>
