gl_rasterizer: Use transformed viewport for depth ranges

Implement depth ranges using the transformed viewport instead of the
generic one. This matches the current Vulkan implementation but doesn't
support negative depth ranges. An update to glad is required for this.

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -933,13 +933,15 @@ void RasterizerOpenGL::SyncViewport() {
             }
             flags[Dirty::Viewport0 + i] = false;
 
-            const Common::Rectangle<f32> rect{regs.viewport_transform[i].GetRect()};
+            const auto& src = regs.viewport_transform[i];
+            const Common::Rectangle<f32> rect{src.GetRect()};
             glViewportIndexedf(static_cast<GLuint>(i), rect.left, rect.bottom, rect.GetWidth(),
                                rect.GetHeight());
 
-            const auto& src = regs.viewports[i];
-            glDepthRangeIndexed(static_cast<GLuint>(i), static_cast<GLdouble>(src.depth_range_near),
-                                static_cast<GLdouble>(src.depth_range_far));
+            const GLdouble reduce_z = regs.depth_mode == Maxwell::DepthMode::MinusOneToOne;
+            const GLdouble near_depth = src.translate_z - src.scale_z * reduce_z;
+            const GLdouble far_depth = src.translate_z + src.scale_z;
+            glDepthRangeIndexed(static_cast<GLuint>(i), near_depth, far_depth);
         }
     }
 }