(GET_CHAR_BEFORE_2): Check multibyte, not

(GET_CHAR_BEFORE_2): Check multibyte, not
target_multibyte.  Even in a unibyte case, return a converted
multibyte char.
(GET_CHAR_AFTER): New macro.
(PATFETCH): Translate via multibyte char.
(HANDLE_UNIBYTE_RANGE): Delete this macro.
(SETUP_MULTIBYTE_RANGE): New macro.
(regex_compile): Setup compiled code so that its multibyteness
matches that of a target.  Fix the handling of "[X-YZ]" using
SETUP_MULTIBYTE_RANGE.
(analyse_first) <charset>: For filling fastmap for all multibyte
characters, don't check by BASE_LEADING_CODE_P.
(re_search_2): Don't check RE_TARGET_MULTIBYTE_P (bufp).  It is
the same as RE_MULTIBYTE_P (bufp) now.
(mutually_exclusive_p): Check by (! multibyte ||
IS_REAL_ASCII (c)).
(TARGET_CHAR_AND_LENGTH): Delete this macro.
(TRANSLATE_VIA_MULTIBYTE): New macro.
(re_match_2_internal): Don't check RE_TARGET_MULTIBYTE_P (bufp).
It is the same as RE_MULTIBYTE_P (bufp) now.
<exactn>: Translate via multibyte.
<anychar>: Fetch a character by RE_STRING_CHAR_AND_LENGTH.  Don't
translate it.
<charset, charset_not>: Fetch a character by
RE_STRING_CHAR_AND_LENGTH.  Translate via multibyte.
<duplicate>: Call bcmp_translate with the last arg `multibyte'.
<wordbound, notwordbound, wordbeg, wordend, syntaxspec,
notsyntaxspec, categoryspec, notcategoryspec> Fetch a character
by GET_CHAR_AFTER.
(bcmp_translate):  Likewise.