Bugfix for bond_style table with MPI

Summary

Very small bug fix - an incorrect MPI datatype was causing undefined behaviour for tabulated bond potentials (bond_style table).

Author(s)

Sam Niblett, LBNL

Licensing

By submitting this pull request, I agree, that my contribution will be included in LAMMPS and redistributed under either the GNU General Public License version 2 (GPL v2) or the GNU Lesser General Public License version 2.1 (LGPL v2.1).

Backward Compatibility

No impact

Implementation Notes

The equilibrium bond length of the tabulated potential (tb->r0) was incorrectly specified as an MPI_INT during a broadcast. Therefore, all non-root processes received a truncated value of this parameter. This simple fix produced the expected behaviour for me.