apm-agent-php: Segfault when `opcache.restrict_api` is used

Describe the bug

With agent v1.9.0 (#1000) we try and call opcache_get_status() to detect if opcache is in a pending restart state.

There’s an option opcache.restrict_api that can be set to restrict which scripts are allowed to call opcache functions. This setting is useful in a multi-tenant environment to restrict opcache management to a few controlled endpoints. When this setting is set those paths not in the whitelist are prevented from calling opcache functions and this appears to trigger a segfault with the APM agent module.

To Reproduce

Steps to reproduce the behavior:

1. Use APM Agent 1.9.0
2. Set opcache.restrict_api to any arbitrary path
3. Enable APM Agent and trigger a render on any path that is not within the above given restrict_api path.

Expected behavior

No segfault should happen, perhaps the detectOpcacheRestartPending() function should just short-circuit and return false if the current script is not within the opcache.restrict_api path.