On arm64, the default build flag is the same as the one from
`go env` which is arm64. So we should use arm64 instead of
aarch64 for both build flag and file name.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Due to an invalid architecture name (arm64), containerd could not build
on aarch64 machines. Fix this by using the correct name of the
architecture for conditional building.
Signed-off-by: Aleksa Sarai <asarai@suse.de>