crypto/sha256,crypto/sha512: test fallback implementations
This will be required for #69536 but is also good hygiene and required
by go.dev/wiki/AssemblyPolicy.
> The code must be tested in our CI. This means there need to be
> builders that support the instructions, and if there are multiple (or
> fallback) paths they must be tested separately.
The new crypto/internal/impl registry lets us select alternative
implementations from both the same package and importers (such as
crypto/sha256 tests once we have crypto/internal/fips/sha256, or
crypto/hmac).
Updates #69592
Updates #69593
Change-Id: Ifea22a9fc9ccffcaf4924ff6bd08da7c9bd39e99
Cq-Include-Trybots: luci.golang.try:gotip-linux-arm64-longtest,gotip-linux-amd64-longtest,gotip-linux-ppc64le_power8,gotip-linux-ppc64_power8
Reviewed-on: https://go-review.googlesource.com/c/go/+/614656
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Daniel McCarney <daniel@binaryparadox.net> Reviewed-by: Michael Pratt <mpratt@google.com> Reviewed-by: Roland Shoemaker <roland@golang.org>
Auto-Submit: Filippo Valsorda <filippo@golang.org>