ufs_public_release: remove libxml2

[climbfuji]

Remove reference to libxml2, this not required for the CCPP static build. Avoids that users need to install libxml2 on their systems for something that doesn't get used at all.

Also updates the submodule pointer for atmos_cubed_sphere following the merge of the fv3dycore scientific documentation, and contains the update of the branch names for ccpp/framework and ccpp/physics from an earlier commit (from ufs_public_release to release/public-v4).

Associated PRs:

NCAR/ccpp-framework#261
#55
ufs-community/ufs-weather-model#46

For regression testing, see ufs-community/ufs-weather-model#46.

[climbfuji]

Ah, I first need to merge ccpp-framework!

…

On Feb 6, 2020, at 6:51 AM, Dusan Jovic ***@***.***> wrote: Merged #55 <#55> into ufs_public_release. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#55?email_source=notifications&email_token=AB5C2RKV3J6L2N5365OK4CLRBQIXZA5CNFSM4KQ4LNK2YY3PNVWWK3TUL52HS4DFWZEXG43VMVCXMZLOORHG65DJMZUWGYLUNFXW5KTDN5WW2ZLOORPWSZGOWOSU66Q#event-3013955450>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB5C2RJVUHPFS2ZADHN2YZDRBQIXZANCNFSM4KQ4LNKQ>.

[DusanJovic-NOAA]

My mistake. Is there a good way to prevent this in future, like blocking a merge somehow?

[climbfuji]

No worries, I created #56 <#56>.

…

On Feb 6, 2020, at 6:58 AM, Dusan Jovic ***@***.***> wrote: My mistake. Is there a good way to prevent this in future, like blocking a merge somehow? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#55?email_source=notifications&email_token=AB5C2RORPSMKTZLY6KA7UVTRBQJO5A5CNFSM4KQ4LNK2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEK7JYGY#issuecomment-582917147>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB5C2RNYZMXI67DDBER7EE3RBQJO5ANCNFSM4KQ4LNKQ>.