mysql-test/r/sp.result:
  New test case for BUG#3583.
  (And current query is now set correctly.)
mysql-test/t/sp.test:
  New test case for BUG#3583.
sql/sp_head.cc:
  Set the thd->query and try to use cached query, if any, when executing a statement.
sql/sp_head.h:
  Extract the sub-query and store in sp_instr_stmt.
sql/sql_cache.cc:
  Keep the net->pkt_nr up-to-date when using query cache.
  This makes it work with stored procedures too.
sql/sql_cache.h:
  Keep the net->pkt_nr up-to-date when using query cache.
  This makes it work with stored procedures too.
sql/sql_yacc.yy:
  Extract the sub-query and store in sp_instr_stmt.
  (And it's never safe to cache references to local variables.)