Update comments and the skip list, maybe some of these tests don't

Update comments and the skip list, maybe some of these tests don't
report failures, we'll see.

Skip certain hopeless tests: compiler and logging.

compiler will likely always show varying leaks since it doesn't work
on a defined set of modules unless -u compiler is specified.  But that
takes forever (we only run with -u network currently).

logging causes hangs when running with -R.