Correct way to specify minimum Perl version required.

[Andy Wardley]

If I have a distribution that requires, say, Perl 5.6.0, then will it suffice
to put "use 5.6.0" at the top of my Makefile.PL, or do I need something else
(in the style of the PREREQ_PM) to tell CPAN testers to stop testing my
modules on older versions of Perl.

A