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

[Bug #21710]

- struct.c: `struct_alloc`

It is possible for a `NEWOBJ` tracepoint call back to write fields
into a newly allocated object before `struct_alloc` had the time
to set the `RSTRUCT_GEN_FIELDS` flags and such.

Hence we can't blindly initialize the `fields_obj` reference to `0`
we first need to check no fields were added yet.

- object.c: `rb_class_allocate_instance`

Similarly, if a `NEWOBJ` tracepoint tries to set fields on the object,
the `shape_id` must already be set, as it's required on T_OBJECT to
know where to write fields.

`NEWOBJ_OF` had to be refactored to accept a `shape_id`.

TestTracepointObj#test_teardown_with_active_GC_end_hook was failing on
some platforms due to a Proc that is not marked being passed around.
Neither rb_tracepoint_new() nor rb_postponed_job_preregister() promise
to mark their callback `void *data`.

https://rubyci.s3.amazonaws.com/osx1300arm/ruby-master/log/20250902T154504Z.fail.html.gz

Add a GC.start to make the test a better detector for this safety issue
and fix it by getting the Proc from an ivar on the rooted module.

As preparation for https://bugs.ruby-lang.org/issues/20205
making sure the test suite is compatible with frozen string
literals is making things easier.

Since 0c2d81dada, not all trace events are cleared during VM teardown.
This causes a crash when there is a tracepoint for
`RUBY_INTERNAL_EVENT_GC_EXIT` active during teardown.

The commit looks like a refactoring commit so I think this change was
unintentional.

[Bug #16682]

This patch contains several ideas:

(1) Disposable inline method cache (IMC) for race-free inline method cache
    * Making call-cache (CC) as a RVALUE (GC target object) and allocate new
      CC on cache miss.
    * This technique allows race-free access from parallel processing
      elements like RCU.
(2) Introduce per-Class method cache (pCMC)
    * Instead of fixed-size global method cache (GMC), pCMC allows flexible
      cache size.
    * Caching CCs reduces CC allocation and allow sharing CC's fast-path
      between same call-info (CI) call-sites.
(3) Invalidate an inline method cache by invalidating corresponding method
    entries (MEs)
    * Instead of using class serials, we set "invalidated" flag for method
      entry itself to represent cache invalidation.
    * Compare with using class serials, the impact of method modification
      (add/overwrite/delete) is small.
    * Updating class serials invalidate all method caches of the class and
      sub-classes.
    * Proposed approach only invalidate the method cache of only one ME.

See [Feature #16614] for more details.

Now, rb_call_info contains how to call the method with tuple of
(mid, orig_argc, flags, kwarg). Most of cases, kwarg == NULL and
mid+argc+flags only requires 64bits. So this patch packed
rb_call_info to VALUE (1 word) on such cases. If we can not
represent it in VALUE, then use imemo_callinfo which contains
conventional callinfo (rb_callinfo, renamed from rb_call_info).

iseq->body->ci_kw_size is removed because all of callinfo is VALUE
size (packed ci or a pointer to imemo_callinfo).

To access ci information, we need to use these functions:
vm_ci_mid(ci), _flag(ci), _argc(ci), _kwarg(ci).

struct rb_call_info_kw_arg is renamed to rb_callinfo_kwarg.

rb_funcallv_with_cc() and rb_method_basic_definition_p_with_cc()
is temporary removed because cd->ci should be marked.