```
scheduler.c:44:5: warning: ignoring return value of ‘write’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   44 |     write(blocking_state->notify_descriptor, "x", 1);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Generating an object_id for any type other than T_OBJECT (and T_CLASS)
will inevitably allocate an IMEMO/fields objects, which isn't supported
in a NEWOBJ tracepoint.

See: https://bugs.ruby-lang.org/issues/21710#note-23

Encodings are RTypedData, not the deprecated RData. Although the
structures are compatible we should use the correct API.

These macros have been defined here and there, so collect them.

It is exported only for the extension library to test, but the method
is no longer used since 29e31e72fb5a14194a78ec974c4ba56c33ad8d45.

Previously we only allocated bignums from the 40 byte sizepool, and
embedded bignum used a fixed size.

The NEWOBJ tracepoint can generate an object_id, that's alright,
what we don't want is actual instance variables.