Disable s3 and ipc executable entry points

cmd/registry-storagedriver-azure/main.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 package main
 
 import (

cmd/registry-storagedriver-filesystem/main.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 package main
 
 import (

cmd/registry-storagedriver-inmemory/main.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 package main
 
 import (

cmd/registry-storagedriver-s3/main.go

@@ -1,3 +1,5 @@
+// +build ignore
+
 package main
 
 import (

cmd/registry/main.go

@@ -15,7 +15,6 @@ import (
 	"github.com/docker/docker-registry/configuration"
 	_ "github.com/docker/docker-registry/storagedriver/filesystem"
 	_ "github.com/docker/docker-registry/storagedriver/inmemory"
-	_ "github.com/docker/docker-registry/storagedriver/s3"
 )
 
 func main() {