tests: avoid few lingering $MAKE redirections These were present in the 'maint' branch, but not in the 'micro' branch. Their occurrences has been found by the 'sc_tests_no_run_make_redirect' maintainer check. * t/fort2.sh: Adjust. * t/preproc-demo.sh: Likewise. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>