HBSD: define HARDENEDBSD in make framework to determine HardenedBSD build

github-issue: #58
build-test: http://nyi-01.build.hardenedbsd.org:8180/jenkins/job/HardenedBSD_Unstable/20/
Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
(cherry picked from commit d290ffcd301547cbae28d7556c8314d9466b3c02)