Remove the per pixel depth option.

Depth calculations are always done in the pixel shader now.

Due to the unpredictability of our zcomploc hacks this commit probably changes the behavior of some games which use zcomploc.

Source/Core/VideoCommon/Src/VertexShaderGen.cpp

@@ -465,6 +465,7 @@ const char *GenerateVertexShaderCode(u32 components, API_TYPE api_type)
 
 	//write the true depth value, if the game uses depth textures pixel shaders will override with the correct values
 	//if not early z culling will improve speed
+	// TODO: Can probably be dropped?
 	if (is_d3d)
 	{
 		WRITE(p, "o.pos.z = " I_DEPTHPARAMS".x * o.pos.w + o.pos.z * " I_DEPTHPARAMS".y;\n");