reflect: change rtype so that it (not *rtype) implements Type
The abi.Type field was changed to *abi.Type, thus the
bitwise representation is the same, many casts are now
avoided and replace by either rtype{afoo} or rfoo.Type.
Change-Id: Ie7643edc714a0e56027c2875498a4dfe989cf7dd
Reviewed-on: https://go-review.googlesource.com/c/go/+/487558
Run-TryBot: David Chase <drchase@google.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>