Fix forward declaration bugs

src/gpu/VirtualFluids_GPU/BoundaryConditions/BoundaryConditionFactory.h

@@ -7,7 +7,7 @@
 
 #include "LBM/LB.h"
 
-class LBMSimulationParameter;
+struct LBMSimulationParameter;
 
 using boundaryCondition = std::function<void(LBMSimulationParameter *, QforBoundaryConditions *)>;
 

src/gpu/VirtualFluids_GPU/KernelManager/LBKernelManager.h

@@ -43,7 +43,7 @@
 class CudaMemoryManager;
 class BoundaryConditionFactory;
 class Parameter;
-class LBMSimulationParameter;
+struct LBMSimulationParameter;
 
 using boundaryCondition = std::function<void(LBMSimulationParameter *, QforBoundaryConditions *)>;