rpm: Generate per distribution and multilib macro files

rpm: Generate per distribution and multilib macro files

The distribution and multilib macro files are required for rpmbuild, on the
target, to work properly.  These override the default settings from the
upstream macro files with the proper values for the OE configuration.

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>