Fix GH-22885: SEGV when setting the comment of a modified zip entry

[khaledalam]

Fixes GH-22885.

[LamentXU123]

Quite a radical fix I think at the first glance. However I do know why your fix is way more bigger than I expected since you've chosen a robuster way I haven't thought of. I will take a look ASAP.

[LamentXU123]

This should target branch 8.4 as a bug fix.
At least for new codes I think adding these hint macros are good practices :/

[LamentXU123]

Suggested change

	exit('failed');
	die('failed');

[LamentXU123]

Given this, I also think we can add a test case where we have a blank comment.
I doubt there is a bug. Try this case:

$zip->open($file);
$zip->setMtimeName('x.txt', 1000000);
$zip->setCommentName('x.txt', '');
$zip->close();

Because I don't think your logic here and line 152 is correct.
You see, in line 66 we have

	/* Avoid a libzip use-after-free when resetting an unchanged inherited comment. */
	if (current_comment && current_comment_len == comment_len
			&& memcmp(current_comment, comment, comment_len) == 0) {
		return true;
	}

a later setCommentName($name, '') hits the equality fast path and returns true without actually removing the original comment.

[LamentXU123]

Suggested change

	exit('failed');
	die('failed');