• Use ourselves as test file instead of /COPYRIGHT, which may or may not be present in the test environment.

• atf-check understands \n in strings, use it.

• Some file systems don't like creating small holes, so create large ones instead. This means we need two variables: ps (page size) is the minimum size of a data region and the alignment for a hole, while hs (hole size) is the minimum size of the holes we create. This makes no difference on FreeBSD but makes it easier to port the test to other platforms.

MFC after: 1 week
Sponsored by: Klara, Inc.