allow ini_set('error_log',...) with in-memory stream

Description

calling ini_set('error_log', $logger) seems to expect $logger to be a filesystem path (or a magic identifer like "syslog").

is it possible to pass in a memory stream?

use-case: in phpunit we want to capture all output a possible code beeing tested might write into error_log.
I have implemented this feature with a tmpfile() in https://github.com/sebastianbergmann/phpunit/pull/6118 but IMO it would be cleaner and more efficient (no filesystem IO) if I could pass in a memory stream like php://memory or php://temp:

        $stream = fopen('php://temp', 'rw');
        $errorLogPrevious = ini_set('error_log', $stream);

首先跟踪 ini_set('error_log', ...) 如何处理文件系统路径以及 "syslog" 等魔法标识符。查看链接的 PHPUnit pull request，了解当前针对 tmpfile() 的 workaround，并定义对 php://memory 或 php://temp 的支持行为，包括如何验证完成情况。