Currently we hardcode the architecture to the `runtime.GOARCH` when
building a docker image, this will result in a confusing info if the
arch in the base image is different from the one on the host.
This PR takes use of the arch data from the base image during the build
process, thus we can get consistent arch info between the base image
and the finally built image.
Signed-off-by: Dennis Chen <dennis.chen@arm.com>
Upstream-commit: 92b17b10bad1f1788419b70db5d6ed9cdf8d15ef
Component: engine
40b08ea4d1