into parts when converting to Unicode.
m_ctype.h:
  Reorganizing mb_wc return codes to be able
  to return "an unassigned N-byte-long character".
sql_string.cc:
  Adding code to detect and properly handle
  unassigned characters (i.e. the those character
  which are correctly formed according to the 
  character specifications, but don't have Unicode
  mapping).
Many files:
  Fixing conversion function to return new codes.
ctype_ujis.test, ctype_gbk.test, ctype_big5.test:
  Adding a test case.
ctype_ujis.result, ctype_gbk.result, ctype_big5.result:
  Fixing results accordingly.


include/m_ctype.h:
  Reorganizing mb_wc return codes to be able
  to return "an unassigned N-byte long character".
  Bug#15375 Unassigned multibyte codes are broken into parts when converting to Unicode.
mysql-test/r/ctype_big5.result:
  Fixing results accordingly.
mysql-test/r/ctype_gbk.result:
  Fixing results accordingly.
mysql-test/r/ctype_ujis.result:
  Fixing results accordingly.
mysql-test/t/ctype_big5.test:
  Adding a test case.
mysql-test/t/ctype_gbk.test:
  Adding a test case.
mysql-test/t/ctype_ujis.test:
  Adding a test case.
sql/sql_string.cc:
  Adding code to detect and properly hanlde
  unassigned characters (i.e. the those character
  which are correctly formed according to the 
  character specifications, but don't have Unicode
  mapping).
strings/ctype-big5.c:
  Fixing conversion function to return new codes.
strings/ctype-bin.c:
  Fixing conversion function to return new codes.
strings/ctype-cp932.c:
  Fixing conversion function to return new codes.
strings/ctype-euc_kr.c:
  Fixing conversion function to return new codes.
strings/ctype-gb2312.c:
  Fixing conversion function to return new codes.
strings/ctype-gbk.c:
  Fixing conversion function to return new codes.
strings/ctype-latin1.c:
  Fixing conversion function to return new codes.
strings/ctype-simple.c:
  Fixing conversion function to return new codes.
strings/ctype-sjis.c:
  Fixing conversion function to return new codes.
strings/ctype-tis620.c:
  Fixing conversion function to return new codes.
strings/ctype-ucs2.c:
  Fixing conversion function to return new codes.
strings/ctype-ujis.c:
  Fixing conversion function to return new codes.
strings/ctype-utf8.c:
  Fixing conversion function to return new codes.