Add support for an rpm-extra-macros config option which can be
used to define some extra macros that need to be set for rootfs
construction to work on the host and that don't really warrant
their own specific named config options to be created.
(From OE-Core rev: 0564f7bbe8e06868e107b70d5abbf3dd6c113bad)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
