Adds a broadcast of the namelist value 'urbantvmapalgo'

[briandobbins]

Adds a broadcast of the namelist value (urbantvmapalgo) after reading it in so it is consistent across all ranks when not using the default value ('nn').

Description of changes

Simple one-line change; a namelist value wasn't being shared with ranks other than the main one reading the namelist. This lead to hangs when trying a different algorithm.

Specific notes

Contributors other than yourself, if any:

CTSM Issues Fixed (include github issue #):
#2533

Are answers expected to change (and if so in what way)?
No

Any User Interface Changes (namelist or namelist defaults changes)?
No

Does this create a need to change or add documentation? Did you do so?
No

Testing performed, if any:
Limited testing, but it's a one-line logical change. If more is needed, let me know. I just did a simple test with and without the change, looking at the values on all ranks.

[billsacks]

Thanks for the fix @briandobbins !

[ekluzek]

@briandobbins I'm rebasing this to come in on b4b-dev, so it can come in quicker.

[wwieder]

Is this ready to merge?

[samsrabin]

@briandobbins Would you mind rebasing this onto ctsm5.3.0 and force-pushing? Not a big deal, but makes it clearer exactly what files are being changed.

I tested git rebase ctsm5.3.0 fix_urbantvmapalgo_broadcast and it worked with no conflicts.

[samsrabin]

@briandobbins Rebase no longer needed; I'll start testing now.

[briandobbins]

Argh, my apologies -- I've just been swamped with deadlines. Before you test, though, there's an additional change needed (to enable 'redist' as an option in the namelist_definition_ctsm.xml file for the urbantvmapalgo option). Happy to add this after tonight, so if you want to delay one more day, or do it yourself, that'd be fine.

Thanks so much!

[samsrabin]

Ah okay, I'll let you handle that. Once you push I'll kick off the testing.