* Optimized the bad-char table of Boyer-Moore

Changed Boyer-Moore's bad-char table code:
- Reduce it to half size if the pattern is ASCII, saving on initialization
- If pattern is ASCII and subject is not, any non-ASCII char can cause a
  full pattern-length shift, even if we haven't indexed the entire pattern.
- Use memset to initialize buffer in the common case where the pattern is
  shorter than the max significant suffix limit.

[Lasse Reichstein, 2008-10-17 10:00:05]

Small code review.