MFC r293048,r293444:

MFC r293048,r293444:

r293048:

- Use a temporary file for the temporary md(4) devices instead of
  hardcoding it
- Remove the temporary file in the cleanup routine

r293444:

- Move functions that might be used in class-specific cleanup functions
  (geom_test_cleanup, etc) down so the testcases don't emit noise when
  bailing
- Conform to the TAP protocol better when dealing with classes that can't
  be loaded and with temporary files that can't be allocated for tracking
  md(4) devices.

git-svn-id: svn://svn.freebsd.org/base/stable/10@294550 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f