[dev.regabi] cmd/compile: replace ir.Name map with ir.NameSet in inlining

As CL 282212 mentioned, we should clean all map[*ir.Name]bool with
ir.NameSet.

Passes toolstash -cmp.

Updates #43819

Change-Id: I1ce5d2055f88539f807dc021cd8e3941b425bc4e
Reviewed-on: https://go-review.googlesource.com/c/go/+/284897


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