Fails to declare test prereqs with old EUMM

Quoth Makefile.PL:

```
  ( $ExtUtils::MakeMaker::VERSION < 6.63_03 ? 'BUILD_REQUIRES' : 'TEST_REQUIRES' ) => {
    'Test::More'       => '0.88',
    'Test::Tester'     => $tt_prereq,
  },
```

BUILD_REQUIRES was added in 6.55_01.  If the version of EUMM is less than that (any default installation of 5.10.0 or lower with no EUMM upgrade), then Test::Tester fails to get declared as a prerequisite.
