top: extend 'zero suppression' scope to several fields

top: extend 'zero suppression' scope to several fields

This commit just tries to parallel the implementations
in the newlib branch. The config file Rc.zero_suppress
will be extended to include both out-of-memory fields.

And while we're at it, we'll also extend zero suppress
to that NI (nice value) field, which already should've
had it. Plus we trade those namespaces custom suppress
logic for our now slightly enhanced make_num function.

Signed-off-by: Jim Warner <james.warner@comcast.net>