Lets ignore autotool generated files (.la .dirstamp .deps) everywhere
rather than hardcoded specific subdirs. We'll never add files with
those names to the source repo, so that should be OK.
We're already ignoring CMakeFiles/ everywhere (since the rule lacks
a leading / anchor), so we can delete the redundant paths.
Rather than hardcode every possible unittest and related files, add
globs that ignore all *_test related paths in the topdir. We won't
be adding paths like that to the source repo, so it should be OK.