1) undoing my fix for BUG#8055 "Trouble with replication from temporary tables and ignores"

and fixing it another way (per Monty; a simpler solution which does not increase the number
of binlog events is to always execute DROP TEMPORARY TABLE IF EXISTS on slave). A new test rpl_drop_temp.
2) fixing BUG#8436 "Multiple "stacked" SQL statements cause replication to stop" by setting
thd->query_length to the length of the query being executed, not counting the next queries
if this is a multi-query. Should also improve display of SHOW PROCESSLIST. A new test rpl_multi_query.



mysql-test/r/drop_temp_table.result:
  back to one single DROP
sql/sql_base.cc:
  undoing the fix I had made some days ago: we are back to one single DROP TEMPORARY TABLE for all temp tables.
sql/sql_parse.cc:
  1) set thd->query_length to the length of the query being executed, excluding the other next queries
  if this is a multi-query. The setting happens ASAP, ie. just after we know it's a multi-query, ie. just after yyparse().
  Don't include the ';' in thd->query_length, because this is not good for storage in binlog.
  2) always execute a DROP TEMPORARY TABLE IF EXISTS on slave, don't skip it even if --replicate-ignore-table

mysql-test/t/rpl_drop_temp-slave.opt

@@ -0,0 +1,2 @@
+--replicate-ignore-table=mysqltest.t2
+