[dev.typeparams] cmd/compile: suppress liveness diagnostics of wrappers

Similar to the previous CL to suppress escape analysis diagnostics for
method wrappers, suppress liveness analysis diagnostics too. It's
hardly useful to know that all of a wrapper method's arguments are
live at entry.

Change-Id: I0d1e44552c6334ee3b454adc107430232abcb56a
Reviewed-on: https://go-review.googlesource.com/c/go/+/330749


Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>