using a hash table instead (and made it work with lex pointers).
Some additional code cleanup too.


sql/sp.cc:
  Fixed the old kludge for pre-loading functions and made it more efficient
  using a hash table instead (and made it work with lex pointers).
  Some additional cleanup of comments too.
sql/sp_head.h:
  Some additional code cleanup.
sql/sql_lex.cc:
  Use hash table for function pre-loading (isntead of list).
sql/sql_lex.h:
  Use hash table for function pre-loading (isntead of list).