Can't compile from source on CentOS with gcc10

[caseyfleeter]

When compiling from source on CentOS 7 (Stanford's Sherlock cluster), gcc9 compilers must be used. This is okay for now, but in the future they may remove support for gcc9. There is an error using gcc10 compilers which seems to be due to a change in Fortran variable assignment error handling.

The change log for gcc10 (https://gcc.gnu.org/gcc-10/changes.html) in the Fortran section, third bullet, says: "Mismatches between actual and dummy argument lists in a single file are now rejected with an error. Use the new option -fallow-argument-mismatch to turn these errors into warnings; this option is implied with -std=legacy. -Wargument-mismatch has been removed."

It might be good to add the new option into the MakeFile so we can compile using gcc10 in the future. Thanks!

[ktbolt]

@caseyfleeter I ran into this problem a while back on MacOS (see #32) and added the -std=legacy option to the CMake files. I can add that for GNU compilers in general. Why do you use make rather than cmake to build the solver?

A better solution is to fix the non-standard Fortran code.

[caseyfleeter]

That makes sense! I was just following the instructions from the file svSolver/BuildWithMake/README-build-linux.txt. This was the best practice when I first joined the lab, but may be outdated now...