Fixing the code to be compatible with nvcc.

ChangeLog

src/functions/tnlMeshFunction.h

src/functions/tnlMeshFunction_impl.h

src/functions/tnlTestFunction_impl.cu

src/matrices/tnlCSRMatrix_impl.h

src/matrices/tnlChunkedEllpackMatrix_impl.h

src/matrices/tnlMatrix_impl.h

src/mesh/grids/tnlGrid1D.h

src/mesh/grids/tnlGrid2D.h

src/mesh/grids/tnlGrid3D.h

src/mesh/grids/tnlNeighbourGridEntityGetter1D_impl.h

src/mesh/grids/tnlNeighbourGridEntityGetter2D_impl.h

src/mesh/grids/tnlNeighbourGridEntityGetter3D_impl.h

src/mesh/grids/tnlTraverser_Grid1D_impl.h

src/mesh/grids/tnlTraverser_Grid2D_impl.h

src/solvers/pde/tnlExplicitUpdater.h

src/solvers/pde/tnlExplicitUpdater_impl.h

src/solvers/pde/tnlLinearSystemAssembler.h

src/solvers/pde/tnlLinearSystemAssembler_impl.h

.../unit-tests/operators/diffusion/tnlLinearDiffusionTest.cu