When computing the dependency graph for the image generation, we need
to take into account the compression type and identify the base type
it relates to. This allow for a more robust graph generation even when
using composed image types.
(From OE-Core rev: 6e7d1de6cc99ed2def346dc40310573f5f0ce5ca)
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>