Makefile: disable 'printvars' and 'show-vars' recipes for Make 4.3

Make 4.3 is buggy and leads to a "Segmentation fault (core dumped)" when
calling 'make printvars' or 'make show-vars', so let's refuse to execute
those recipes if Make 4.3 by adding 'check-make-version' recipe as
depedendency of 'printvars' and 'show-vars' as suggested by Yann E. Morin.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>