cmd/compile: remove check that Zero's arg has the correct base type
It doesn't have to. The type in the aux field is authoritative.
There are cases involving casting from interface{} where pointers
have a placeholder pointer type (because the type is not known when
the IData op is generated).
The check was introduced in CL 13447.
Fixes #39459
Change-Id: Id77a57577806a271aeebd20bea5d92d08ee7aa6b
Reviewed-on: https://go-review.googlesource.com/c/go/+/239817
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>