remove containers_image_rekor_stub build tag

It was added for debian so they could build without the deps but this is
no longer needed. Get rid of it to simplify the codebase.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

README.md

@@ -61,7 +61,6 @@ or use the build tags described below to avoid the dependencies (e.g. using `go
 - `containers_image_openpgp`: Use a Golang-only OpenPGP implementation for signature verification instead of the default cgo/gpgme-based implementation;
 the primary downside is that creating new signatures with the Golang-only implementation is not supported.
 - `containers_image_storage_stub`: Don’t import the `containers-storage:` transport in `github.com/containers/image/transports/alltransports`, to decrease the amount of required dependencies.  Use a stub which reports that the transport is not supported instead.
-- `containers_image_rekor_stub`: Don't import sigstore/reckor code, all rekor operations will return an error code
 
 ## [Contributing](CONTRIBUTING.md)
 

signature/internal/rekor_set.go

@@ -1,5 +1,3 @@
-//go:build !containers_image_rekor_stub
-
 package internal
 
 import (

signature/internal/rekor_set_stub.go

@@ -1,14 +0,0 @@
-//go:build containers_image_rekor_stub
-
-package internal
-
-import (
-	"crypto/ecdsa"
-	"time"
-)
-
-// VerifyRekorSET verifies that unverifiedRekorSET is correctly signed by publicKey and matches the rest of the data.
-// Returns bundle upload time on success.
-func VerifyRekorSET(publicKeys []*ecdsa.PublicKey, unverifiedRekorSET []byte, unverifiedKeyOrCertBytes []byte, unverifiedBase64Signature string, unverifiedPayloadBytes []byte) (time.Time, error) {
-	return time.Time{}, NewInvalidSignatureError("rekor disabled at compile-time")
-}

signature/internal/rekor_set_test.go

@@ -1,5 +1,3 @@
-//go:build !containers_image_rekor_stub
-
 package internal
 
 import (

signature/sigstore/rekor/rekor.go

@@ -1,5 +1,3 @@
-//go:build !containers_image_rekor_stub
-
 package rekor
 
 import (

signature/sigstore/rekor/rekor_stub.go

@@ -1,16 +0,0 @@
-//go:build containers_image_rekor_stub
-
-package rekor
-
-import (
-	"fmt"
-	"net/url"
-
-	signerInternal "github.com/containers/image/v5/signature/sigstore/internal"
-)
-
-func WithRekor(rekorURL *url.URL) signerInternal.Option {
-	return func(s *signerInternal.SigstoreSigner) error {
-		return fmt.Errorf("rekor disabled at build time")
-	}
-}