cmd/compile: add ir.ContainsClosure

cmd/compile: add ir.ContainsClosure

And use it to unify all codes that need parent/closure checking.

Change-Id: I0b0aa1b007598668dff2c4bee31e21f0fb3830ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/650315
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>