EXTRA_IMAGEDEPENDS is used to ensure things like qemu-native are built and
these are not strictly dependencies of the do_rootfs task. This patch
moves them to the do_build task allowing bitbake a little more flexibility
about when things need to get built by.
I noticed this when qemu-native failed to build and a rootfs was not generated
which is not the intended behaviour.
Also update the syntax to use appendVarFlag instead of get/setVarFlag
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
