rsx: Maintenance fixes [4]

[kd-11]

• Do not enable host fp16 by default. Instead, move to GPU tab as a shader precision setting. More options will be moved under this switch in future. Native fp16 is actually too precise, compared to what RSX expects. That is what is causing the minor glitches when it is enabled. However, it generates much better shaders than the emulated fp16 version so I have left it in for users with weaker GPUs.
• Implement RSX-compliant polygon offset for the major GPU vendors. Polygon offset unfortunately is not portable, and different GPUs and drivers will have different calibration constants that need to be calculated and scaled to match RSX. I have covered AMD and NVIDIA on both windows and linux. Intel has not been tested, but should work just fine under vulkan. Intel + OpenGL is unsupported.

Fixes #11678
Fixes #11350
Fixes #11959
Fixes #12008
Fixes #11917

[Linear524]

This PR fixes flickering shadows in God of War Ascension for my rigs (I use XeonV4 CPUs with TSX on @ GTX 1080) ! :)
Thank yo KD-11 ! :)

[marcin-przywoski]

I think this commit has increased performance a lot in older R&C games on my 5950X. The 3rd planet in R&C2 (the space station) does not have 51 fps at the beginning but very close to locked 60 now. I think I'm seeing the same improvements in ToD

[Jorforit]

I don't understand the solution, it says to disable native fp16/ implement RSX-compliant polygon. what does it mean?
I don't know why but i also can't find the box to disable this/ don't know what an RSX-compliant polygon means.
Can someone help?

[Darkhost1999]

You don't need to do anything just update RPCS3 to reap the reward