libfwrapper.c is a C file that wraps the LAMMPS library API
in src/library.h so that it can be called from Fortran.

See the couple/simple/simple.f90 program for an example of a Fortran
code that does this.

See the README file in that dir for instructions on how to build a
Fortran code that uses this wrapper and links to the LAMMPS library.
