plan tests $n, test_module 'php4'

[Doug MacEachern]

i added some sugar so we can get rid of ExtModules::TestEnv, instead of:

plan tests => 1, \&ExtModules::TestEnv::has_php4;

you can now say:
 plan tests $n, test_module 'php4'

or

 plan tests $n, [qw(php4 rewrite)]

etc.