This plumbing is required for cmake/ctest to recognise and report
skipped tests.
Now skipped tests in cmake ci jobs are reported like so:
```
Start 7: libarchive_test_acl_platform_posix1e_read
7/785 Test #7: libarchive_test_acl_platform_posix1e_read ................................***Skipped 0.02 sec
```
And there is a list of skipped tests shown at the end of the test run.