cmd/compile: pass arguments as register parameters to StaticCall.

cmd/compile: pass arguments as register parameters to StaticCall.

Additional register-parameter plumbing, not all the way to the end;
if you test register parameter-passing, it fails mid-compilation.

For #40724.

Change-Id: Ibb675022c9156779a451726329890e52fca1cb33
Reviewed-on: https://go-review.googlesource.com/c/go/+/293398
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>