Update CMakeLists.txt - append extra flags for gnu 10+ with mpich

[climbfuji]

Description
This PR fixes #1417. Instead of overwriting the compile flags for the Fortran targets, it appends the compatibility flags for gnu 10 with mpich to the existing flags. The syntax I used is available since cmake 2.8.12.

Resolves #1417

How Has This Been Tested?
Tested on Derecho with [email protected] and [email protected].

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes (not run)

[thomas-robinson]

@climbfuji do you need a patch for 2023.03?

[climbfuji]

Is 2023.04 going to be a major update or will it be easy for us to move up to that with the next spack-stack release?

…

On Nov 22, 2023, at 8:56 AM, Tom Robinson ***@***.***> wrote: @climbfuji <https://github.com/climbfuji> do you need a patch for 2023.03? — Reply to this email directly, view it on GitHub <#1418 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB5C2RMYSDC6YTTPABYIIU3YFYOCVAVCNFSM6AAAAAA7WOMLZCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQMRTGAZTMNBQGA>. You are receiving this because you were mentioned.

[thomas-robinson]

2023.04 is mostly supporting a coupler update and updating variable names to no longer be Fortran keywords. It should be an easy update from 2023.03.

[climbfuji]

In that case I think we don't need a bug fix release for 2023.03 - thanks!

[climbfuji]

Thanks very much @rem1776! Will this be included in [email protected]?

[rem1776]

Yes this will be in 2023.04. Thanks for the fix!