tests: implement is_newest as an auxiliary script, not shell function This will allow to also use it in the makefile recipes used in our test cases. * t/ax/test-init.sh (is_newest): Remove. * t/ax/is_newest: New script. * Makefile.am (EXTRA_DIST): Add it. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>