When recursing into a directory to delete it, start by chmod'ing it to
0700. This fixes an issue where kyua is able to run, but not debug, a
test case that creates unwriteable directories, because when debugging
it tries (and fails) to delete the directory after the test completes.
This includes a test case which I haven't been able to test since we
don't build or install kyua's own tests.
MFC after: 1 week
Sponsored by: Klara, Inc.