Complex return types were not stored correctly in the mysql.proc table.


mysql-test/r/sp.result:
  New testcase for BUG2772.
mysql-test/t/sp.test:
  New testcase for BUG2772.
sql/sp_head.cc:
  Pick up character set for "returns" types in functions and add it separately,
  since it's missed when extracting the type during the parser. (Due to LALR
  behaviour.)
sql/sp_head.h:
  Save the character set for returns clause in functions.
sql/sql_yacc.yy:
  Pick up character set for "returns" types in functions since it's missed otherwise.
  (Due to LALR behaviour.)