cmd/compile: print readable function name in error message
cmd/compile: print readable function name in error message

i.e.
from "function %!s(*Node=0xc0003b48c0) cannot have ABI wrappers", to "function xxFunctionName cannot have ABI wrappers".

Change-Id: I83cfdf1916e82ab1455db8032153d9cdae85250d
GitHub-Last-Rev: 87b077653f8731be511861d968bd31d58744b386
GitHub-Pull-Request: golang/go#56428
Reviewed-on: https://go-review.googlesource.com/c/go/+/445516
Auto-Submit: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
Run-TryBot: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>
Reviewed-by: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>

golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go