_multibuild is not created for 000productcompose

[fcrozat]

Unlike when generating 000product, packagelistgen is not generating _multibuild for 000productcompose.

[adrianschroeter]

hm, yes, the idea was that you should be able to select the flavors you actually want to build via that.
You can have a plenty of flavors defined, but may only want to build a few of them.

We could of course also create a _multibuild file based on all flavors defined in the compose file ...