Do not clear all the font's glyph caches with single-step zoom
operators if the area does not change font size when doing so.
See D16785 for more details.
Differential Revision: https://developer.blender.org/D16785
Reviewed by Campbell Barton
This is the conventional way of dealing with unused arguments in C++,
since it works on all compilers.
Regex find and replace: `UNUSED\((\w+)\)` -> `/*$1*/`