Fixes for bugs in the usage of IO_CACHE

Docs/manual.texi:
  Fixed the TRUNCATE syntax + Changelog
include/my_sys.h:
  Added my_b_vprintf
mysys/mf_iocache2.c:
  Added my_b_vprintf
mysys/my_vsnprintf.c:
  Fixed fatal (new) bug
mysys/thr_lock.c:
  Cleanup
readline/bind.c:
  cleanup
scripts/Makefile.am:
  Added mysqldumpslow
sql-bench/crash-me.sh:
  Fixed TRUNCATE
sql/log.cc:
  bug fix
sql/log_event.cc:
  Removed compiler warnings
sql/log_event.h:
  Fixed non portable header in binary dump
sql/mf_iocache.cc:
  cleanup
sql/mysqld.cc:
  Fixed loop problem on NT
sql/slave.cc:
  cleanup
sql/sql_class.cc:
  Fixed typos
sql/sql_parse.cc:
  cleanup
sql/sql_select.cc:
  bugfix
sql/sql_table.cc:
  cleanup
sql/sql_yacc.yy:
  Changed ALTER TABLE ... ORDER BY to get fewer warnings
sql/unireg.cc:
  cleanup
sql/unireg.h:
  Added missing define

sql/sql_table.cc

@@ -1446,7 +1446,6 @@ int mysql_alter_table(THD *thd,char *new_db, char *new_name,
       mysql_bin_log.write(&qinfo);
     }
     goto end_temporary;
-    DBUG_RETURN(0);
   }
 
   intern_close_table(new_table);		/* close temporary table */