DX9: Fix Renderer::SetLineWidth like hrydgard suggested ;)
DX9: Build fix. Also removed the Renderer::SetLineWidth implementation since it wasn’t really useful.
VideoCommon: Use integer arithmetic instead of floating point arithmetic when dealing with EFB scales.
Should fix problems caused by EFB scales other than Native (excluding fractional!). Test whether this fixes games which work fine with native EFB resolution but show glitches with higher internal resolutions.
Also fixed numerous warnings.