message: Fix derivatives in vulkan shader debugger
diff: @@ -4564,6 +4564,11 @@ ShaderDebugTrace *VulkanReplay::DebugPixel(uint32_t eventId, uint32_t x, uint32_
  var.columns = param.compCount & 0xff;
  var.type = param.varType;
  + deriv.ddxcoarse = var;
  + deriv.ddycoarse = var;
  + deriv.ddxfine = var;
  + deriv.ddyfine = var;
  +
  const uint32_t comp = Bits::CountTrailingZeroes(uint32_t(param.regChannelMask));
  const uint32_t elemSize = VarTypeByteSize(param.varType);
  