cmd/dist, internal/platform: enable internal linking feature and test on loong64

cmd/dist, internal/platform: enable internal linking feature and test on loong64

Change-Id: Ifea676e9eb44281465832fc4050f6286e50f4543
Reviewed-on: https://go-review.googlesource.com/c/go/+/533717
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
Reviewed-by: sophie zhao <zhaoxiaolin@loongson.cn>
Reviewed-by: Qiqi Huang <huangqiqi@loongson.cn>