nf_fread error checking

[jcwarner]

In function ROMS/Utility/nf_fread2d, lines 223:237 *

      status=nf90_noerr
      IF (InpThread) THEN
        status=nf90_get_var(ncid, ncvarid, wrk, start, total)
        IF (status.eq.nf90_noerr) THEN
          ...
        END IF
      END IF

      ...

      IF (status.ne.nf90_noerr) RETURN

If the file is not read correctly, then "status" will not equal nf90_noerr, and the code will return. But we need to have the value of "nf_fread" set to = the value of status before the return happens. IF the file is read correctly, then at the bottom of nf_fread2d we have:

      nf_fread2d=status

so that is ok.

Suggest that we add a line

      nf_fread2d=status

before the return statement. This also needs to be addressed in read 3d, 4d.