Another workaround for https://bugzilla.altlinux.org/show_bug.cgi?id=39663

This function's got its argument order chosen for "aesthetical"
reason of $(2) following $(1) in the macros but the logical order
is exactly the opposite: we care for kernel flavour much more than
for module set (which is dependent upon it).

So while silent dropout of kernel-image if KFLAVOURS is set
but KMODULES is empty could be fixed by testing for $(2) only,
it looks like a good time to fix this discrepancy altogether.

An initial draft of it was done half a year ago but several tricky
thingies had kept the code from showing up as it was rather brittle
and incomplete.

This implementation involves quite a few changes all over the place
but finally works good enough for live and installer images.

Please pay attention to the versions of these packages:
- installer-feature-setup-plymouth (0.3.2-alt1+)
- branding-altlinux-sisyphus (20110706-alt2+ if used)
- plymouth (0.8.3-alt20.git20110406+)

See also:
- http://www.altlinux.org/Branding
- http://www.altlinux.org/Plymouth

This further refines the modular build by making
metadata being a clearly separated feature rather
than having to rely on runtime tests, and also by
moving the code which cares for kernel bits of base
installation (.base list) in a feature of its own.

There's more to it but let's get the ball rolling first.