kcmp selftests: make run_tests fix

make run_tests need the target is run_tests instead of run-tests
Also gcc output should be kcmp_test. Fix these two issues.

Signed-off-by: Dave Young <dyoung@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>