Allow interruption of IO waits.

[ioquatix]

Ruby's IO model allows IO#close to interrupt all pending read/write/wait operations. The Fiber Scheduler did not adopt this model initially, but after some time it's finally caused some compatibility issues for code which expects signalling between IO#close and in-flight operations (to be forcefully interrupted).

This introduces the changes required to support IO interrupting, by passing the IO instance to the rb_io_interruptable_operation, which doesn't exist yet, such that any kind of interruption within Ruby can propagate out.

Types of Changes

• Bug fix.

Contribution

• I added tests for my changes.
• I tested my changes locally.
• I agree to the Developer's Certificate of Origin 1.1.

[ioquatix]

No longer required, it's an implicit part of the scheduler hook.