cleaning tamc.h : collect previous comments

[jm-c]

@jm-c just a comment/suggestion: These variables defined as parameters in tamc.h:

      integer nyears_chkpt
      integer nmonths_chkpt
      integer ndays_chkpt
      integer ngeom_chkpt
      integer ncheck_chkpt

are not used anywhere in the code, as far as I can see. They do not produce unused-warning messages, because of the parameter statements, but they are unused, nevertheless. Maybe we can remove them in the PR as well?

Originally posted by @mjlosch in #579 (comment)