Remove some unneeded initializers.

Remove some unneeded initializers.

Some people might argue for more initializers to be "safer",
but I actually prefer to leave things this way. It saves
typing, but the real benefit is that the things that do
require initialization stand out so we know to watch them
carefully. And with valgrind, we actually get to catch
errors earlier if we *don't* initialize them. So that can
be "safer" ironically enough.