build: Show summary in "make help" output.
build: Show summary in "make help" output.

The summary is useful not just at build time, so display it
in the "make help" output.

Signed-off-by: James O. D. Hunt <348fbaadfbada55ea105602bf5609e23ac1c4898@intel.com>

clearcontainers/runtime,chavafg/runtime,clearcontainers/runtime,devimc/runtime,chavafg/runtime,devimc/runtime