Currently the netcdf-fortran build supports both fortran 03 and fortran 77 builds.

Really, there's no need to continue supporting the non-03 builds. Fortran 03 is widespread. No science users need to be stuck with a fortran 77 compiler any more.

SIgnificant simplification of the code and build is possible by removing this legacy support, which would hopefully help make netcdf-fortran more agile and easier to maintain and improve.