Reverted the default setting of newton_pair off for FixGPU; newton_pair can be set to be on via command-line options of package gpu

src/GPU/fix_gpu.cpp

@@ -127,7 +127,7 @@ FixGPU::FixGPU(LAMMPS *lmp, int narg, char **arg) :
   _gpu_mode = GPU_NEIGH;
   _particle_split = 1.0;
   int nthreads = 0;
-  int newtonflag = force->newton_pair;
+  int newtonflag = 0;
   int threads_per_atom = -1;
   double binsize = 0.0;
   char *opencl_args = nullptr;