Ignore unreasonable timestep values.

This fixes #5202 (Crisis Core stuttering) and improves Mana Khemia's "Who
are you?" sound effect while loading savedata.  May also improve Monster
Hunter's similar issue.
Properly exit error screen when hitting cancel.

Fixes #3351.
Merge pull request #5209 from unknownbrackets/ui-tweaks

Properly exit error screen when hitting cancel
Merge pull request #5208 from unknownbrackets/display-minor

Ignore unreasonable timestep values