run-tests.php: Add a flag similar to --asan that skips tests when run under Valgrind

Description

I just ran 11k tests under Valgrind to try and find issues with one of my big PRs, and any test excepting an OOM failure will either time out or use all the memory before being killed.

It would be great if those could be skipped and not accidentally triggered.

Some relevant tests:

• ext/standard/tests/gh14643_longname.phpt
• Zend/tests/bug79836_4.phpt
• tests/basic/bug67198.phpt (maybe)
• tests/basic/enable_post_data_reading_05.phpt (maybe)

Other tests are those opening PHP procs and timing out:

• ext/standard/tests/file/proc_open01.phpt
• ext/standard/tests/http/gh11274.phpt
• ext/standard/tests/streams/bug64433.phpt
• ext/standard/tests/url/get_headers_error_003.phpt

And some tests seem to be bogus with Valgrind or an issue that we cannot fix:

• ext/standard/tests/mail/mail_basic2.phpt
• ext/standard/tests/mail/mail_variation2.phpt

先在 run-tests.php 中阅读现有 --asan 标志的解析和应用方式。然后在 Valgrind 下运行列出的 .phpt 测试，以确认存在问题的情况，接着验证新的 Valgrind 相关标志会跳过预期的测试，且不会影响正常的测试运行。