Always find largest drm buf, to fix some cases
when there are multiple planes and we accidentally
capture a drm buf that isn't the target buf.
We always want the full SCREEN drm buf.
If there is only one monitor connected and it's rotated then
the drm buf will also be rotated. This only the case with AMD and
only when using one monitor!
To fix this, we perform color conversion with an opengl shader
which allows us to also rotate the texture.
VAAPI supports rotation but it's not implemented by AMD at least.
Performance seems to be the same as when using VAAPI, even when
GPU usage is 100%.
