[dev.typeparams] runtime: allow deferproc split stack

deferproc was not allowed to split stack because it had a special
stack layout, where the go'd function's arguments were passed on
stack but not included in the signature (therefore the stack map).
Now it no longer has argument, so it does not need to be nosplit.

Change-Id: I6d4b5302bd6fea6642bb4202984d86e3ebbc9054
Reviewed-on: https://go-review.googlesource.com/c/go/+/325920


Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>