Had to add a cahing mechanism which is in parts an ugly kludge, but it will be
reworked once the real SP caching is implemented.


mysql-test/r/sp.result:
  New function tests.
mysql-test/t/sp.test:
  New function tests.
sql/sp.cc:
  Big rehack of mysql.proc table usage strategy and adding a function cache
  mechanism, since we need to read used functions from the db before doing anything else
  when executing a query. (This cache is temporary and will probably be replaced by
  the real thing later.)
sql/sp.h:
  New (temporary) FUNCTION caching functions.
sql/sp_head.cc:
  Fixed some bugs in the function and procedure execution.
  Disabled some data collections that's not used at the moment.
sql/sp_head.h:
  Fixed some bugs in the function and procedure execution.
  Disabled some data collections that's not used at the moment.
sql/sql_class.h:
  Added SP function cache list to thd.
sql/sql_lex.cc:
  Added SP function name list to lex.
sql/sql_lex.h:
  Added SP function name list to lex.
sql/sql_parse.cc:
  Read used FUNCTIONs from db and cache them in thd before doing anything else
  in a query execution. (This is necessary since we can't open mysql.proc during
  query execution.)
sql/sql_yacc.yy:
  Collect used function names in lex.