Fix PCRE2 sys build for FreeBSD

[Rot127]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the rizin book with the relevant information (if needed)

Detailed description

Fix #4185 (comment)

Test plan

Locally tested

Closing issues

...

[Rot127]

@arrowd Added a blind fix with 90c0207

Couldn't test it yet, because my internet connection is pretty slow at the moment and setting up FreeBSD takes quite long.
So if you are faster, feel free to drop a note here.

[arrowd]

Yep, I made the same change locally to fix the build. Thanks!

[XVilka]

Please open a new PR from the rizinorg account, and with dist- branch to trigger everything.

[Rot127]

Dist-fuzz build was green in #4310
Only using this for auto-merge