runtime: remove odd-forcing of hash constants

runtime: remove odd-forcing of hash constants

We don't multiply by them any more, so no need to make them odd.

Suggested by me here in 2021:
https://go-review.googlesource.com/c/go/+/280372/comment/1a86b8aa_f64310bf/
Never got around to it until now.

Change-Id: Iddc675e6a18b4a7a785acbf77c96e127003cc3c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/579116
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>