[parrot/parrot] c5e9a0: [core] Optimize utf8_substr. do not use utf8 itera...

[GitHub]

  Branch: refs/heads/rurban/utf8_substr-gh1097
  Home:   https://github.com/parrot/parrot
  Commit: c5e9a0fa44ab5625cb04dadaf7ae8833c76c964c
      https://github.com/parrot/parrot/commit/c5e9a0fa44ab5625cb04dadaf7ae8833c76c964c
  Author: Reini Urban <rurban at cpanel.net>
  Date:   2014-10-12 (Sun, 12 Oct 2014)

  Changed paths:
    M src/string/encoding/shared.c
    M src/string/encoding/unicode.h
    M src/string/encoding/utf8.c

  Log Message:
  -----------
  [core] Optimize utf8_substr. do not use utf8 iterator

Use a new utf8_offset function instead. This can be optimized
further if we can guarantee word alignment of the buffers.
Add a special utf8 vtable method for substr.
This is a hot item for perl6, see GH #1097

Do not export the Parrot_utf8skip table anymore, not used
by parrot, nqp, perl6.