Bug#22043 MySQL don't add "USE <DATABASE>" before "DROP PROCEDURE EXISTS"

- CREATE PROCEDURE stores database name based on query context instead
  of 'current database' as set by 'USE' according to manual.
  The bug reporter interpret the filtering statements as bug for
   DROP PROCEDURE based on this behavior.
- Removed the code which changes db context.
- Added code to check that a valid db was supplied.  


mysql-test/r/rpl_sp.result:
  - Added test case (result)
mysql-test/t/rpl_sp.test:
  - Added test case
sql/sp.cc:
  - Removed code for changing current db context.
sql/sql_parse.cc:
  - Added code to check if a valid db was supplied.

sql/sp.cc

@@ -494,17 +494,10 @@ db_create_routine(THD *thd, int type, sp_head *sp)
   char definer[USER_HOST_BUFF_SIZE];
   char old_db_buf[NAME_LEN+1];
   LEX_STRING old_db= { old_db_buf, sizeof(old_db_buf) };
-  bool dbchanged;
   DBUG_ENTER("db_create_routine");
   DBUG_PRINT("enter", ("type: %d name: %.*s",type,sp->m_name.length,
                        sp->m_name.str));
 
-  if ((ret= sp_use_new_db(thd, sp->m_db, &old_db, 0, &dbchanged)))
-  {
-    ret= SP_NO_DB_ERROR;
-    goto done;
-  }
-
   if (!(table= open_proc_table_for_update(thd)))
     ret= SP_OPEN_TABLE_FAILED;
   else
@@ -629,8 +622,6 @@ db_create_routine(THD *thd, int type, sp_head *sp)
 
 done:
   close_thread_tables(thd);
-  if (dbchanged)
-    (void) mysql_change_db(thd, old_db.str, 1);
   DBUG_RETURN(ret);
 }