Use correct type for ContainerExecAttach

ContainerExecAttach used `types.ExecConfig` instead of `types.ExecStartCheck`,
which is the type that's expected by the `/exec/execid/start` API endpoint.

Investigating when this inconsistency was introduced, I found that the client has
sent the additional properties since its first imlpementation in
c786a8ee5e9db8f5f609cf8721bd1e1513fb0043.

The `postContainerExecStart()` at that time used the "jobs" package, which
only took the information from the body that was needed (`Detach` and `Tty`).

Commit 24425021d26f29a475702064181e6c99fb6bd1c5 refactored the Exec commands
to remove the "jobs", and introduced the `ExecStartCheck` type, but failed to
update the `cli.hijack()` call with the new type.

The change in this patch should not affect compatibility with older clients,
as the additional information from the `ExecConfig` type is not used (the
API server already decodes to the `ExecStartCheck` type).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client/container_exec.go

@@ -35,7 +35,7 @@ func (cli *Client) ContainerExecStart(ctx context.Context, execID string, config
 // It returns a types.HijackedConnection with the hijacked connection
 // and the a reader to get output. It's up to the called to close
 // the hijacked connection by calling types.HijackedResponse.Close.
-func (cli *Client) ContainerExecAttach(ctx context.Context, execID string, config types.ExecConfig) (types.HijackedResponse, error) {
+func (cli *Client) ContainerExecAttach(ctx context.Context, execID string, config types.ExecStartCheck) (types.HijackedResponse, error) {
 	headers := map[string][]string{"Content-Type": {"application/json"}}
 	return cli.postHijacked(ctx, "/exec/"+execID+"/start", nil, config, headers)
 }

client/interface.go

@@ -45,7 +45,7 @@ type ContainerAPIClient interface {
 	ContainerCommit(ctx context.Context, container string, options types.ContainerCommitOptions) (types.IDResponse, error)
 	ContainerCreate(ctx context.Context, config *container.Config, hostConfig *container.HostConfig, networkingConfig *network.NetworkingConfig, containerName string) (container.ContainerCreateCreatedBody, error)
 	ContainerDiff(ctx context.Context, container string) ([]container.ContainerChangeResponseItem, error)
-	ContainerExecAttach(ctx context.Context, execID string, config types.ExecConfig) (types.HijackedResponse, error)
+	ContainerExecAttach(ctx context.Context, execID string, config types.ExecStartCheck) (types.HijackedResponse, error)
 	ContainerExecCreate(ctx context.Context, container string, config types.ExecConfig) (types.IDResponse, error)
 	ContainerExecInspect(ctx context.Context, execID string) (types.ContainerExecInspect, error)
 	ContainerExecResize(ctx context.Context, execID string, options types.ResizeOptions) error