Fix OMP threading issue with dfresh and dfsalt

[dabail10]

Found an OMP threading bug with two of the SIMIP variables.

• Developer(s): D. Bailey

• Please suggest code Pull Request reviewers in the column at right.

• Are the code changes bit for bit, different at roundoff level, or more substantial? BFB, except for two history variables: siflsaltbot and siflfwbot.

• Please include the link to test results or paste the summary block from the bottom of the testing output below.

• Does this PR create or have dependencies on Icepack or any other models? N

• Is the documentation being updated with this PR? (Y/N) N
  If not, does the documentation need to be updated separately at a later time? (Y/N) N

Note: "Documentation" includes information on the wiki and .rst files in doc/source/,
which are used to create the online technical docs at https://readthedocs.org/projects/cice-consortium-cice/.

• Other Relevant Details:

[mhrib]

Nice catch!
It was also one of the issues that causes problems with evp-kernel (#205) and for my tests of "HYCOM forcing read" (#224).

rgs
Mads