Remove usage of pkg sockets and tlsconfig.

- Use the ones provided by docker/go-connections, they are a drop in replacement.
- Remove pkg/sockets from docker.
- Keep pkg/tlsconfig because libnetwork still needs it and there is a
  circular dependency issue.

Signed-off-by: David Calavera <david.calavera@gmail.com>

docs/registry.go

@@ -23,8 +23,8 @@ import (
 	"github.com/docker/distribution/registry/client/transport"
 	"github.com/docker/docker/dockerversion"
 	"github.com/docker/docker/pkg/parsers/kernel"
-	"github.com/docker/docker/pkg/tlsconfig"
 	"github.com/docker/docker/pkg/useragent"
+	"github.com/docker/go-connections/tlsconfig"
 )
 
 var (

docs/service_v1.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/docker/docker/pkg/tlsconfig"
 	"github.com/docker/docker/reference"
+	"github.com/docker/go-connections/tlsconfig"
 )
 
 func (s *Service) lookupV1Endpoints(repoName reference.Named) (endpoints []APIEndpoint, err error) {

docs/service_v2.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/docker/docker/pkg/tlsconfig"
 	"github.com/docker/docker/reference"
+	"github.com/docker/go-connections/tlsconfig"
 )
 
 func (s *Service) lookupV2Endpoints(repoName reference.Named) (endpoints []APIEndpoint, err error) {