Clean up ddb(4) slightly

[ngie]

Summary

Clean up ddb(4) slightly

• Delete empty Li macro uses [1]
• Attempt to clarify "show lock" subcommand by being more terse/direct. This addresses an issue with a contraction [2].

MFC after: 1 week
Reported by: make manlint [1], igor [2]
Sponsored by: Dell EMC Isilon

Test Plan

• igor
• make manlint

[wblock]

As long as this still renders correctly, works for me.

[ngie]

In D9858#203988, @wblock wrote:

As long as this still renders correctly, works for me.

Removing Li changes this:

where[/u] [pid | tid] [,count]

to this:

where[/u] [pid | tid][,count]

(note the space change after tid])