Determine if pnetcdf is in the mksurfdata_esmf build

[slevis-lmwg]

Motivated by this comment:
Determine whether pnetcdf is in the mksurfdata_esmf build (this issue), in order to propagate that info from the build phase to the gen_namelist phase to the fortran phase of mksurfdata_esmf (to be addressed in #1748).

Relates to #1748 where we are figuring out how to run mksurfdata_esmf on izumi.

[slevis-lmwg]

I'm wondering whether the fortran can read env_mach_specific.xml for pnetcdf to avoid having to add that info in the namelist or the separate .txt file.