update USER-OMP code for shear history neighbor refactoring

src/USER-OMP/npair_half_size_bin_newtoff_omp.cpp

src/USER-OMP/npair_half_size_bin_newton_omp.cpp

src/USER-OMP/npair_half_size_bin_newton_tri_omp.cpp

src/USER-OMP/npair_half_size_nsq_newtoff_omp.cpp

src/USER-OMP/npair_half_size_nsq_newton_omp.cpp

src/USER-OMP/pair_gran_hertz_history_omp.cpp

src/USER-OMP/pair_gran_hooke_history_omp.cpp