Call standalone ./Build before calling ./Build test

per [Module::Build](https://metacpan.org/module/Module::Build) spec, `./Build` should be called before running `./Build test`.

`./Build test` without `./Build` happened to work with the current version of Module::Build but it was an undocumented behavior.

Rationale: [Some builds](https://travis-ci.org/tokuhirom/Minilla/jobs/5701450) using a variant of Module::Build breaks because of the omission of the standalone `./Build` process.