sync up HookState with OCI spec State

`HookState` struct should follow definition of `State` in runtime-spec:

* modify json name of `version` to `ociVersion`.
* Remove redundant `Rootfs` field as rootfs can be retrived from
`bundlePath/config.json`.

Signed-off-by: Zhang Wei <zhangwei555@huawei.com>

libcontainer/configs/config.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/opencontainers/runtime-spec/specs-go"
 )
 
 type Rlimit struct {
@@ -243,13 +244,7 @@ func (hooks Hooks) MarshalJSON() ([]byte, error) {
 }
 
 // HookState is the payload provided to a hook on execution.
-type HookState struct {
-	Version    string `json:"ociVersion"`
-	ID         string `json:"id"`
-	Pid        int    `json:"pid"`
-	Root       string `json:"root"`
-	BundlePath string `json:"bundlePath"`
-}
+type HookState specs.State
 
 type Hook interface {
 	// Run executes the hook with the provided state.