distance restraints with multiple pairs segv with OpenMP
When distance restraints are used with multiple pair distances contributing to one restraint, mdrun will produce a segmentation fault when such pairs in such restraints end up on different OpenMP threads
fixed multiple distance restraints with OpenMP
Distance restraints with multiple pairs (the same label) are no
longer split over multiple OpenMP threads. Some (beneficial)
reorganization of the bonded thread division was required to do this,
most importantly: removed calc_one_bond_foreign.