Revert "cmd/compile: rework marking of dead hidden closure functions"

Revert "cmd/compile: rework marking of dead hidden closure functions"

This reverts commit http://go.dev/cl//484859

Reason for revert: causes linker errors in a number of google-internal tests.

Change-Id: I322252f784a46d2b1d447ebcdca86ce14bc0cc91
Reviewed-on: https://go-review.googlesource.com/c/go/+/485755
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>