fix memory corruption issue in fix reax/c/species

      if (iarg+ntypes+1 > narg) error->all(FLERR,"Illegal fix reax/c/species command");

      eletype = (char**) malloc(ntypes*sizeof(char*));

      int len;

      for (int i = 0; i < ntypes; i ++) {

        eletype[i] = (char*) malloc(2*sizeof(char));

        len = strlen(arg[iarg+1+i])+1;

        eletype[i] = (char*) malloc(len*sizeof(char));

        strcpy(eletype[i],arg[iarg+1+i]);

      }

      eleflag = 1;