lib/sys_info: handle sys_info_mask==0 case

Generalization of panic_print's dump function [1] has been merged, and
this patchset is to address some remaining issues, like adding note of the
obsoletion of 'panic_print' cmdline parameter, refining the kernel
document for panic_print, and hardening some string management.


This patch (of 4):

It is a normal case that bitmask parameter is 0, so pre-initialize the
names[] to null string to cover this case.

Also remove the superfluous "+1" in names[sizeof(sys_info_avail) + 1],
which is needed for 'strlen()', but not for 'sizeof()'.

Link: https://lkml.kernel.org/r/20250825025701.81921-1-feng.tang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20250825025701.81921-2-feng.tang@linux.alibaba.com
Link: Link: https://lkml.kernel.org/r/20250703021004.42328-1-feng.tang@linux.alibaba.com [1]
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Askar Safin <safinaskar@zohomail.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>