i965: Track sRGB colorspace state on fast clear.
This commit adds sRGB colorspace tracking during fast clears. By using that, we can avoid the gen9 workaround for sRGB-enabled blending on fast cleared framebuffers.
It only avoids the resolve when GL_FRAMEBUFFER_SRGB
was enabled at the time of the fast clear. If it was disabled, and we are now about to render with blending into an sRGB surface, we have to do a resolve first, otherwise the hardware would convert the clear color into sRGB when filling non-clear CCS blocks, which is not desired.
Hopefully the case where we fast clear the sRGB surface with GL_FRAMEBUFFER_SRGB
enabled is the common case, so this patch might make a difference. Otherwise, it's probably not worth the extra tracking.
CC @nchery @jekstrand