cmd/compile: remove support for old-style bounds check calls

cmd/compile: remove support for old-style bounds check calls

This CL rips out the support for old-style assembly stubs.

We need to keep the Go stubs for wasm support.

Change-Id: I23d6d9f2f06be1ded8d22b3e0ef04ff6e252a587
Reviewed-on: https://go-review.googlesource.com/c/go/+/682402
Reviewed-by: Austin Clements <austin@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>