cmd/compile/internal/types: remove Type.sym and rename Type.nod to Type.obj
Now that Ntype is gone, we no longer require separate sym and nod
fields for Type. It's now always the case that t.sym == t.nod.Sym(),
or that t.sym and t.nod are both nil.
While here, rename nod to obj, to better reflect that in fact it's
always an object (i.e., *ir.Name), not merely a type literal (which no
longer exists in package ir).
Change-Id: Iba4c1590ca585b816ff6b70947ad2a1109918955
Reviewed-on: https://go-review.googlesource.com/c/go/+/405656
Run-TryBot: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>