cmd/compile: rework marking of dead hidden closure functions
This patch generalizes the code in the inliner that marks unreferenced
hidden closure functions as dead. Rather than doing the marking on the
fly (previous approach), this new approach does a single pass at the
end of inlining, which catches more dead functions.
Fixes #59638.
Updates #59404.
Updates #59547.
Change-Id: I54fd63e9e37c9123b08a3e7def7d1989919bba91
Reviewed-on: https://go-review.googlesource.com/c/go/+/484859 Reviewed-by: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>