more typecasts to double to avoid 32-bit int overflows when computing memory usage

src/USER-MISC/pair_local_density.cpp

@@ -881,7 +881,7 @@ void PairLocalDensity::unpack_reverse_comm(int n, int *list, double *buf) {
 
 double PairLocalDensity::memory_usage()
 {
-  double bytes = maxeatom * sizeof(double);
+  double bytes = (double)maxeatom * sizeof(double);
   bytes += (double)maxvatom*6 * sizeof(double);
   bytes += (double)2 * (nmax*nLD) * sizeof(double);
   return bytes;