Correct a variable name in a ele_ngi check that was in a #ifdef DDEBUG in assemble/Advection_Diffusion_CG.F90
Correct a variable name in a ele_ngi check that was in a #ifdef DDEBUG
in assemble/Advection_Diffusion_CG.F90

rjferrier/fluidity,iakovos-panourgias/fluidity,rjferrier/fluidity,iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity,jrper/fluidity,rjferrier/fluidity,jjo31/ATHAM-Fluidity,iakovos-panourgias/fluidity,jrper/fluidity,jjo31/ATHAM-Fluidity,jjo31/ATHAM-Fluidity,jjo31/ATHAM-Fluidity,jrper/fluidity,jrper/fluidity,rjferrier/fluidity,jrper/fluidity,iakovos-panourgias/fluidity,iakovos-panourgias/fluidity,rjferrier/fluidity