base.bbclass: extend PACKAGECONFIG to also allow RRECOMMENDS
It can be useful to add RRECOMMENDS to packages created, based
on certain PACKAGECONFIGs.
In particular where a package depends on certain linux kernel
infrastructure (kernel modules) which might or might not be
built as a module, being able to RRECOMMENDS instead of
RDEPENDS on the relevant packages avoids build failures in
case those modules are built statically into the kernel, i.e.
in case no package is being created for them.
Add another field to the PACKAGECONFIG syntax to achieve just
that.
Signed-off-by: André Draszik <adraszik@tycoint.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
