Must use explicit scope on virtual functions when called from constructor

src/compute_msd_chunk.cpp

@@ -48,7 +48,7 @@ ComputeMSDChunk::ComputeMSDChunk(LAMMPS *lmp, int narg, char **arg) :
   idchunk = utils::strdup(arg[3]);
 
   firstflag = 1;
-  init();
+  ComputeMSDChunk::init();
 
   // create a new fix STORE style for reference positions
   // id = compute-ID + COMPUTE_STORE, fix group = compute group