Make sure tmpfs mounts are unmounted
Make sure tmpfs mounts are unmounted

Add cleanup routines to ensure tmpfs mounts are forcibly unmounted if
the test fails, and also fix a leak of a mount point.  The current Kyua
cleanup automation does not do this any longer for simplicity reasons.

jmmv/kyua,jmmv/kyua,jmmv/kyua,jmmv/kyua