WL#5083: Error for character set conversion failure

The following should be an error, not a warning:    
    
   mysql> create table tj (s1 char(10) character set sjis);    
   Query OK, 0 rows affected (0.52 sec)    
    
   mysql> set sql_mode=ansi;    
   Query OK, 0 rows affected (0.03 sec)    
    
   mysql> insert into tj values (0x8080);    
   Query OK, 1 row affected, 1 warning (0.00 sec)    
    
   (The above causes a warning 1366 "Incorrect
   string value ..." which is an error if strict.)

   What [some Japanese users] really want is that we accept the    
   junk character, but I can't think of a good    
   way, and they indicated that "at least" an    
   error should be there.   

This is applicable for all character sets.

Why this was moved from WL#3090
-------------------------------

This requirement was originally part of
WL#3090 Japanese Character Set Adjustments.
The earlier suggestion was that there should
be an error for Japanese character sets, but
in MySQL private emails with subject line
"Re: WL#3090 Japanese Character Set Adjustments"
this conversation took place:
PETER> * Give an error message for a conversion failure,
PETER> even if sql_mode <> strict.
PETER> This was a request from long ago.
PETER> I'm not sure whether anybody cares any more.
PETER> It's easy, but I wonder whether we should make
PETER> this change for all character
PETER> sets, or only for sjis, ujis, cp932, and eucjpms.

BAR> I don't like to make the Japanese character sets make in a special way
BAR> regarding error/warning. Perhaps we should move it into a separate WL,
BAR> for all character sets.