This also removes the need to compute the persmat and saves some memory
from the `ViewInfos` struct. This is needed to allow multiview support.
Initial testing found no major performance regression during vertex
heavy workload.
Test file: {F13610017}
Results:
| Platform | Master | Split Matrix|
| Linux + Mesa + AMD W6600 | 48 fps | 47 fps |
| Macbook Pro M1 | 50 fps | 51 fps |
| Linux + NVidia 1080Ti | 51 fps | 52 fps |
| Linux + Radeon Vega 64 | 25.6 fps | 26.7 fps |
Increased precision when far from origin:
{F13610024}
{F13610025}
Reviewed By: jbakker
Differential Revision: https://developer.blender.org/D16125
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*/`
