Automatic merge from submit-queue

add owners file for strategic merge patch

`staging/src/k8s.io/apimachinery/pkg/util/strategicpatch` is the strategic merge patch pkg
`staging/src/k8s.io/apimachinery/pkg/util/mergepatch` is the util pkg for strategic merge patch and json merge patch
`staging/src/k8s.io/apimachinery/third_party/forked/golang/json/OWNERS` is another util pkg used by strategic merge patch

cc: @pwittrock @grodrigues3 @apelisse