compare footprint: add sanity args files

Added sanity args to be used by the compare footprint.
Please notice that compare footprint use sanitycheck to
build footprint apps for base commit and for current commit.
This in order to collect the information and generate the diff.

Change-Id: I6f86bbfa020999b3f26e93a608fc7b34ee508e10
Signed-off-by: Javier B Perez <javier.b.perez.hernandez@intel.com>