LibSoftGPU: Avoid copying data when doing triangle rasterization

Several large-ish objects shouldn't be copied to the stack when a
reference will do.

Userland/Libraries/LibSoftGPU/Device.cpp

@@ -184,9 +184,9 @@ void Device::rasterize_triangle(const Triangle& triangle)
  return;
 
  // Vertices
- Vertex const vertex0 = triangle.vertices[0];
- Vertex const vertex1 = triangle.vertices[1];
- Vertex const vertex2 = triangle.vertices[2];
+ Vertex const& vertex0 = triangle.vertices[0];
+ Vertex const& vertex1 = triangle.vertices[1];
+ Vertex const& vertex2 = triangle.vertices[2];
 
  // Calculate area of the triangle for later tests
  FloatVector2 const v0 = vertex0.window_coordinates.xy();
@@ -262,7 +262,7 @@ void Device::rasterize_triangle(const Triangle& triangle)
  auto stencil_buffer = m_frame_buffer->stencil_buffer();
 
  // Stencil configuration and writing
- auto const stencil_configuration = m_stencil_configuration[Face::Front];
+ auto const& stencil_configuration = m_stencil_configuration[Face::Front];
  auto const stencil_reference_value = stencil_configuration.reference_value & stencil_configuration.test_mask;
 
  auto write_to_stencil = [](StencilType* stencil_ptrs[4], i32x4 stencil_value, StencilOperation op, StencilType reference_value, StencilType write_mask, i32x4 pixel_mask) {