readelf.c: Use unsigned long to iterate over num_syms

readelf.c: Use unsigned long to iterate over num_syms

process_symbol_table () has

  unsigned long num_syms;
  ...
  for (si = 0, psym = symtab; si < num_syms; si++, psym++)

We should use unsigned long to iterate over num_syms.

	* readelf.c (process_symbol_table): Use unsigned long for si.