cmd/compile: convert reassociation optimizations to typed aux
cmd/compile: convert reassociation optimizations to typed aux

Passes toolstash-check.

Change-Id: I85a161c4e1c29e06e3f7e6ad4a59ff8cc51c7296
Reviewed-on: https://go-review.googlesource.com/c/go/+/229683
Run-TryBot: Josh Bleecher Snyder <cdc248cc4d32e4fbfe04e45228163bcecd48a0b9@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>

CAFxX/go,golang/go,akutz/go,CAFxX/go,akutz/go,akutz/go,cloudflare/go,CAFxX/go,golang/go,akutz/go,golang/go,akutz/go,CAFxX/go,nawawi/go,CAFxX/go,golang/go,cloudflare/go,nawawi/go,cloudflare/go,golang/go,cloudflare/go,golang/go,nawawi/go,nawawi/go,nawawi/go,CAFxX/go,golang/go,CAFxX/go,akutz/go,golang/go,cloudflare/go,akutz/go,cloudflare/go,cloudflare/go,nawawi/go,nawawi/go,cloudflare/go,CAFxX/go,akutz/go,nawawi/go