update hfg: fix unused variables

generate/requirements.txt

operators/curl_curl/N1E1ElementwiseCurlCurl.cpp

operators/curl_curl/N1E1ElementwiseCurlCurl.hpp

...curl/noarch/N1E1ElementwiseCurlCurl_toMatrix_macro_3D.cpp

operators/diffusion/P1ElementwiseDiffusion.cpp

operators/diffusion/P1ElementwiseDiffusion.hpp

...usion/noarch/P1ElementwiseDiffusion_toMatrix_macro_2D.cpp

...usion/noarch/P1ElementwiseDiffusion_toMatrix_macro_3D.cpp

operators/div_k_grad/P1ElementwiseDivKGrad.cpp

operators/div_k_grad/P1ElementwiseDivKGrad.hpp

operators/div_k_grad/P2ElementwiseDivKGrad.cpp

operators/div_k_grad/P2ElementwiseDivKGrad.hpp

...s/div_k_grad/avx/P1ElementwiseDivKGrad_apply_macro_2D.cpp

...s/div_k_grad/avx/P1ElementwiseDivKGrad_apply_macro_3D.cpp

...ivKGrad_computeInverseDiagonalOperatorValues_macro_2D.cpp

...ivKGrad_computeInverseDiagonalOperatorValues_macro_3D.cpp

...s/div_k_grad/avx/P2ElementwiseDivKGrad_apply_macro_2D.cpp

...s/div_k_grad/avx/P2ElementwiseDivKGrad_apply_macro_3D.cpp

...ivKGrad_computeInverseDiagonalOperatorValues_macro_2D.cpp

...ivKGrad_computeInverseDiagonalOperatorValues_macro_3D.cpp