Problem: The "regex" library written by Henry Spencer
does not support tricky character sets like UCS2.
Fix: convert tricky character sets to UTF8 before calling
regex functions.


mysql-test/r/ctype_uca.result:
  Adding tests
mysql-test/r/ctype_ucs.result:
  Adding tests
mysql-test/r/ctype_utf8.result:
  Adding tests
mysql-test/r/func_regexp.result:
  Adding tests
mysql-test/t/ctype_uca.test:
  Adding tests
mysql-test/t/ctype_ucs.test:
  Adding tests
mysql-test/t/ctype_utf8.test:
  Adding tests
mysql-test/t/func_regexp.test:
  Adding tests
sql/item_cmpfunc.cc:
  - Adding new method Item_func_regex::regcomp()
  to share more code between fix_fields() and val_int()
  - Adding conversion from ASCII-incompatible charsets like UCS2
  to UTF8, because the "regexp" does not support these charsets
  - Additional optimization: calculate flags for regcomp only
    once in fix_fields, instead of every regcomp()
sql/item_cmpfunc.h:
  Adding prototypes for new members and methods
mysql-test/include/ctype_regex.inc:
  New BitKeeper file ``mysql-test/include/ctype_regex.inc''
  
  Moving common regular expression tests into a separate
  file and uncluding it into func_regexp and into many ctype_xxx tests.