MFC: r256561

Prevent an unlikely, but real double free issue in gvinum(8).

Coverity ID: 1018965
MFC: r265535

- Sprinkle const and static as appropriate.
- Fix whitespace bugs.
- Remove pointless returns in void functions.
- Nuke pointless switch cases mirroring the default.

Sponsored by:	Bally Wulff Games & Entertainment GmbH