Remove inline build of Parallel IO. Use PIO as an external dependency.

[aerorahul]

Description of changes

This PR:

• removes the git submodule of ParallelIO
• Depends on externally built parallel IO. It is referenced via the environment variable PIO_ROOT, and follows standard installation structure include/ and lib/

Specific notes

Contributors other than yourself, if any:

CMEPS Issues Fixed (include github issue #):

Are changes expected to change answers?

• bit for bit
• different at roundoff level
• more substantial

Any User Interface Changes (namelist or namelist defaults changes)?

• Yes
• No

Testing performed if application target is CESM:(either UFS-S2S or CESM testing is required):

• (required) CIME_DRIVER=nuopc scripts_regression_tests.py
  • machines:
  • details (e.g. failed tests):
• (required) CESM testlist_drv.xml
  • machines and compilers:
  • details (e.g. failed tests):
• (optional) CESM prealpha test
  • machines and compilers
  • details (e.g. failed tests):

Testing performed if application target is UFS-S2S:

• (required) UFS-S2S testing
  • description:
  • details (e.g. failed tests):

Hashes used for testing:

• CESM:
  • repository to check out: https://github.com/ESCOMP/CESM.git
  • branch: nuopc_dev
  • hash:
• UFS-S2S, then umbrella repostiory to check out and associated hash:
  • repository to check out:
  • branch: feature/no-pio
  • hash:dde421d
  • PR

[junwang-noaa]

Code changes look good to me. The PR needs to be committed with s2s ESCOMP#199 after s2s RT tests are done.