sstatesig.py: Add handling for machine specific module dependencies

sstatesig.py: Add handling for machine specific module dependencies

Adding dependencies on machine specific recipes from generic packages
causes a rebuild of the generic package per machine if using signatures
for the stamp files which is unacceptable.

We need to declare that RRECOMMENDS on kernel-module-* are safe
and that we shouldn't care about these machine specific dependencies
from a stamp perspective. This change adds code which does this.

It depends on a change in bitbake to expose the dataCache object
which can be used to make the calculations we need to allow this to
work correctly.

(From OE-Core rev: 91fc672756d45086cdf4e9c6de8e920dcd8cd14e)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>