Fix two problems with REG_ICASE that were introduced with the addition of

Fix two problems with REG_ICASE that were introduced with the addition of
multibyte character support:
- In CHadd(), avoid writing past the end of the character set bitmap when
  the opposite-case counterpart of wide characters with values less than
  NC have values greater than or equal to NC.
- In CHaddtype(), fix a braino that caused alphabetic characters to be
  added to all character classes! (but only with REG_ICASE)

PR:		71367