crypto/elliptic: drop hidden Inverse and CombinedMult methods
These methods were previously used by crypto/ecdsa, but now not even
ecdsa_legacy.go uses them. Neither were ever documented.
Inverse was available only on P256() and only on amd64 and arm64, so
hopefully no one used it. CombinedMult was always available on all
curves, so it's possible some application might have used it, but all
the samples on GitHub I can find copied the old crypto/ecdsa package,
which does a conditional interface upgrade with a fallback, so they
won't break.
Change-Id: I6a6a4656ee1ab98438ca0fb20bea53b229cd7e71
Reviewed-on: https://go-review.googlesource.com/c/go/+/640116 Reviewed-by: Daniel McCarney <daniel@binaryparadox.net> Reviewed-by: Junyang Shao <shaojunyang@google.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Ian Lance Taylor <iant@google.com>