NAG doesn't like the way we read the ecosystem namelist from a single string
containing many namelists (and carriage returns)... in fact, PGI can't read the
namelist either. The two errors are

NAG: Invalid character '
' in NAMELIST input

PGI: end of file reached without finding group

For NAG, this error triggers an abort in POP; for PGI, POP silently uses the
default namelist values (as set in the Fortran code) rather than reading
anything from pop_in.

I thought I had a clever work around -- turn nl_buffer into an array, with each
element containing a separate namelist. This fixes the issue in NAG and PGI,
but gfortran now displays the same silent error of just using the POP defaults
for everything except the namelist in nl_buffer(1).

I'm fairly sure this is a gfortran bug.