Fixed compilation issue in Xcode 16 Beta due to a missing #include

[progrmr]

Description of the change

File RollbarCrashMachineContext.c not compiling with Xcode 16 beta 5, error: ucontext64_t was undefined.
Added #include <sys/_types/_ucontext64.h> to fix.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Maintenance
• New release

Related issues

Shortcut stories and GitHub issues (delete irrelevant)

• Fix [SC-]
• Fix Merge (override with) branch 'vNext-2.0.0' #1

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer

[matux]

Confirmed, this fixes the compilation issue. Thank you @progrmr!