[loader] Fix detection of JIT enabled

[iamluc]

Description

Testing PHP 8.4 with Ondrej PPA, tracer was disabled because opcache.jit is an empty string

Reviewer checklist

• [ ] Test coverage seems ok.
• [ ] Appropriate labels assigned.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 74.82%. Comparing base (ab52de5) to head (fc04956).

Additional details and impacted files

[](https://app.codecov.io/gh/DataDog/dd-trace-php/pull/2971?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog) ```diff @@ Coverage Diff @@ ## master #2971 +/- ## ========================================= Coverage 74.82% 74.82% Complexity 2741 2741 ========================================= Files 110 110 Lines 10863 10863 ========================================= Hits 8128 8128 Misses 2735 2735 ``` | [Flag](https://app.codecov.io/gh/DataDog/dd-trace-php/pull/2971/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog) | Coverage Δ | | |---|---|---| | [tracer-php](https://app.codecov.io/gh/DataDog/dd-trace-php/pull/2971/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog) | `74.82% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog#carryforward-flags-in-the-pull-request-comment) to find out more. ------ [Continue to review full report in Codecov by Sentry](https://app.codecov.io/gh/DataDog/dd-trace-php/pull/2971?dropdown=coverage&src=pr&el=continue&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog). > **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog) > `Δ = absolute (impact)`, `ø = not affected`, `? = missing data` > Powered by [Codecov](https://app.codecov.io/gh/DataDog/dd-trace-php/pull/2971?dropdown=coverage&src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog). Last update [ab52de5...fc04956](https://app.codecov.io/gh/DataDog/dd-trace-php/pull/2971?dropdown=coverage&src=pr&el=lastupdated&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DataDog).

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