[D3D12] ROV sample depth via ddxy(z), DSV depth bias cleanup

src/xenia/gpu/draw_util.cc

@@ -136,6 +136,11 @@ bool IsRasterizationPotentiallyDone(const RegisterFile& regs,
   return true;
 }
 
+// https://docs.microsoft.com/en-us/windows/win32/api/d3d11/ne-d3d11-d3d11_standard_multisample_quality_levels
+const int8_t kD3D10StandardSamplePositions2x[2][2] = {{4, 4}, {-4, -4}};
+const int8_t kD3D10StandardSamplePositions4x[4][2] = {
+    {-2, -6}, {6, -2}, {-6, 2}, {2, 6}};
+
 bool IsPixelShaderNeededWithRasterization(const Shader& shader,
                                           const RegisterFile& regs) {
   assert_true(shader.type() == xenos::ShaderType::kPixel);