Backported fix from 4.0 which caused core dumps for some complex queries.

Docs/manual.texi:
  Fixed example
sql/mysqld.cc:
  Cleanup

Docs/manual.texi

@@ -31150,7 +31150,7 @@ mysql> select TRUNCATE(1.999,1);
         -> 1.9
 mysql> select TRUNCATE(1.999,0);
         -> 1
-mysql> select TRUNCATE(-1,999,1);
+mysql> select TRUNCATE(-1.999,1);
         -> -1.9
 @end example
 

sql/mysqld.cc

@@ -1121,7 +1121,8 @@ void end_thread(THD *thd, bool put_in_cache)
 inline void kill_broken_server()
 {
   /* hack to get around signals ignored in syscalls for problem OS's */
-  if (unix_sock == INVALID_SOCKET || (!opt_disable_networking && ip_sock ==INVALID_SOCKET))
+  if (unix_sock == INVALID_SOCKET ||
+      (!opt_disable_networking && ip_sock == INVALID_SOCKET))
   {
     select_thread_in_use = 0;
     kill_server((void*)MYSQL_KILL_SIGNAL); /* never returns */
@@ -1592,8 +1593,8 @@ pthread_handler_decl(handle_shutdown,arg)
   abort_loop = 1;
 
   // unblock select()
-  so_cancel( ip_sock);
-  so_cancel( unix_sock);
+  so_cancel(ip_sock);
+  so_cancel(unix_sock);
 
   return 0;
 }

sql/opt_range.cc

@@ -1285,7 +1285,8 @@ and_all_keys(SEL_ARG *key1,SEL_ARG *key2,uint clone_flag)
   }
   if (key1->type == SEL_ARG::MAYBE_KEY)
   {
-    key1->left= &null_element; key1->next=0;
+    key1->right= key1->left= &null_element;
+    key1->next= key1->prev= 0;
   }
   for (next=key1->first(); next ; next=next->next)
   {