Support 'type C comparable' properly by using the same logic as for
'type T error', since ErrorType and ComparableType are entirely
analogous.
Added support for 'any' type as well, as requested by Robert. (For the
future - we can't currently have 'any' anywhere other than in a
constraint.)
Fixes#47966
Change-Id: I68bd284ced9a8bfca7d2339cd576f3cb909b1b83
Reviewed-on: https://go-review.googlesource.com/c/go/+/345174
Trust: Dan Scales <danscales@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
