Fix potential OOB when checking for trailing spaces

[cmb69]

If path_len is zero, we must not access path, let alone try to subtract -1 from it.

Since path and path_len are supposed to come from a zend_string, this is not a security issue.

---

Note that I'm not 100% sure whether the patch is correct, since php_win32_check_trailing_space apparently does not only check for trailing spaces, but also for leading spaces.

[cmb69]

Need to check the failing tests.

[cmb69]

php-src/win32/winutil.c

Lines 57 to 71 in 7512685

	int php_win32_check_trailing_space(const char * path, const size_t path_len)
	{/*{{{*/
	if (path_len > MAXPATHLEN - 1) {
	return 1;
	}
	if (path) {
	if (path[0] == ' ' || path[path_len - 1] == ' ') {
	return 0;
	} else {
	return 1;
	}
	} else {
	return 0;
	}
	}/*}}}*/

Okay, classic C style function which checks if there is a leading or trailing space. So far, so good. However, why would it return zero if path == NULL, but one, if the path is too long? The commit message isn't particularly revealing about the handling of the edge cases.

Anyhow, I'm mostly concerned about avoiding the OOB reads, and like to target PHP-8.3, so I'm trying to stick closely to the current behavior.

[Girgias]

Looks reasonable to me as a backport fix.