When new container image add into lxc-host-image-demo, existing
image will not build.

In case of:
CONTAINER_IMAGES ?= "agl-container-cluster:guest-image-cluster-demo \
                     agl-container-ivi:guest-image-ivi-demo \
"

agl-container-ivi:guest-image-ivi-demo will be building,
but agl-container-cluster:guest-image-cluster-demo will not be building.

This patch fix issue for the build dependency creation to guests.

Bug-AGL: SPEC-4109

Signed-off-by: Naoto Yamaguchi <naoto.yamaguchi@aisin.co.jp>
Change-Id: I2ed6f91f0d4db90f337a6148d6630f85c1b5c97d