Port to blueback

[apcraig]

PR checklist

• Short (1 sentence) summary of your PR:
  Port to blueback
• Developer(s):
  apcraig
• Suggest PR reviewers from list in the column to the right.
• Please copy the PR test results link or provide a summary of testing completed below.
  Full test suites run on blueback with 5 compilers, most tests run fine, a few fail as might be expected
• How much do the PR code changes differ from the unmodified code?
  • bit for bit
  • different at roundoff level
  • more substantial
• Does this PR create or have dependencies on Icepack or any other models?
  • Yes
  • No
• Does this PR update the Icepack submodule? If so, the Icepack submodule must point to a hash on Icepack's main branch.
  • Yes
  • No
• Does this PR add any new test cases?
  • Yes
  • No
• Is the documentation being updated? ("Documentation" includes information on the wiki or in the .rst files from doc/source/, which are used to create the online technical docs at https://readthedocs.org/projects/cice-consortium-cice/. A test build of the technical docs will be performed as part of the PR testing.)
  • Yes
  • No, does the documentation need to be updated at a later time?
    • Yes
    • No
• Please document the changes in detail, including why the changes are made. This will become part of the PR commit log.

Port to blueback, new Cray EX4000 on intel, gnu, cray, nvhpc, aocc compilers.