runtime: port memmove, memclr to register ABI on s390x
This allows memmove and memclr to be invoked using the new
register ABI on s390x.
Update #40724
Change-Id: I2e799aac693ddd693266c156c525d6303060796f
Reviewed-on: https://go-review.googlesource.com/c/go/+/719424 Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Vishwanatha HD <vishwanatha.hd@ibm.com> Reviewed-by: Keith Randall <khr@google.com>