[Classic renderer] Pixel aspect ratio is not an exact 8:7, causing uneven rendering

[getphobo]

Here's an issue I found when experimenting with different display resolutions and the Vulkan and classic renderer -- I was looking to get the most even-looking picture, and this is what I got.

When using the classic renderer, with the 'Logical display width' being set to 292.571 (8:7 * 256) and 'Render height' to 1680 (7 * 240), it is always exactly one pixel being rendered less wide than all the others, causing the 256 emulated pixels to become 2047 pixels wide instead of the 2048 I would get on Vulkan.

That would mean that there is some rounding issue or a wrong factor being applied. For a perfect 8:7 pixel aspect ratio, the classic renderer would have to occupy 2048 * 1680 pixels for the 256 * 240 px menu background screen.

This seems to be the reason why the bottom bar is never rendered evenly. Perhaps you might want to look into this?