Avoid `Segmentation fault` with PHP 5.5.14

When running `vendor/bin/phpunit -c phpunit.xml.dist Tests/libphonenumber/Tests/geocoding/PhoneNumberOfflineGeocoderTest.php` under PHP 5.5.14 a `Segmentation fault` is the result (Line 95 is the cause).

The problem is that `Locale::getDisplayRegion` is being called with the first argument being NULL.