[dev.typeparams] cmd/compile: allow nil Syms in Sym.Less
Allows sorting interfaces that contain embedded anonymous types.
Fixes #46556.
Change-Id: If19afa1d62432323b2e98957087867afbf3f9097
Reviewed-on: https://go-review.googlesource.com/c/go/+/324812
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Dan Scales <danscales@google.com>