a DECLARE ? HANDLER FOR stmt.


mysql-test/r/sp-error.result:
  New test case for BUG#8776 (check format of sqlstates in handler declarations).
mysql-test/t/sp-error.test:
  New test case for BUG#8776 (check format of sqlstates in handler declarations).
sql/share/errmsg.txt:
  New error message for malformed SQLSTATEs.
sql/sp_pcontext.cc:
  Added function for checking SQLSTATE format.
sql/sp_pcontext.h:
  Added function for checking SQLSTATE format.
sql/sql_yacc.yy:
  Check format of SQLSTATE in handler declaration.