The cap_dns tests require Internet access. Currently they fail when
that's not available, which for CI purposes is undesirable. Let's
instead skip the tests if none of the non-casper name/addr lookups
succeed.
To that end:
- Convert the tests to ATF so that skipping is easier to implement.
- Break up the tests into separate test cases.
- If one of the system (i.e., non-casper) lookup functions fails, skip
the test if all of them failed, otherwise fail the tests, since
partial failure indicates something is flaky and deserves a closer
look.
Reviewed by: oshogbo
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D39241
80b9892380