Merge pull request #134 from k-takata/fix-segv-in-error-str

Fix SEGV in onig_error_code_to_str() (Fix #132)
bitset_and(BitSetRef dest, BitSetRef bs)
{
  int i;
  for (i = 0; i < BITSET_SIZE; i++) { dest[i] &= bs[i]; }
}

bitset_and(BitSetRef dest, BitSetRef bs)
{
  int i;
  for (i = 0; i < BITSET_SIZE; i++) { dest[i] &= bs[i]; }
}
