Crashes with stored procedure return non-string values
  Also fixes Bug#2773


mysql-test/r/information_schema.result:
  Bug#3788
    Fix results for bugfix
mysql-test/r/sp.result:
  Bug#3788
    Tests for Bug
    Fix results for bugfix
mysql-test/t/sp.test:
  Bug#3788
    New tests for bug
sql/item.cc:
  Fix unrelated crash in view test with --ps-protocol.
sql/item_func.cc:
  Bug#3788
    Alter how SP function result types are handled.
sql/item_func.h:
  Bug#3788
    Alter how SP function result types are handled.
sql/mysql_priv.h:
  Bug#3788
    Prototypes for new global functions
sql/sp.cc:
  Bug#3788
    Alter how function return type is reported
sql/sp_head.cc:
  Bug#3788
    Change how function return types are stored for SPs
sql/sp_head.h:
  Bug#3788
    Change how function return types are stored for SPs
sql/sql_parse.cc:
  Bug#3788
    Split out field construction into its own function
sql/sql_table.cc:
  Bug#3788
    Split out field preparation code into its own function
sql/sql_yacc.yy:
  Bug#3788
    Change how function return types are stored for SPs
sql/unireg.cc:
  Bug#3788
    Add assertion check