If you start Ruby with `--yjit-disable`, the `+YJIT` shouldn't be
added until `RubyVM::YJIT.enable` is actually called. Otherwise
it's confusing in crash reports etc.

Co-authored-by: Jean Boussier <jean.boussier@gmail.com>

YJIT: Let RubyVM::YJIT.enable respect --yjit-stats

We've long had a size restriction on the code memory region such that a
u32 could refer to everything. This commit capitalizes on this
restriction by shrinking the size of `CodePtr` to be 4 bytes from 8.

To derive a full raw pointer from a `CodePtr`, one needs a base pointer.
Both `CodeBlock` and `VirtualMemory` can be used for this purpose. The
base pointer is readily available everywhere, except for in the case of
the `jit_return` "branch". Generalize lea_label() to lea_jump_target()
in the IR to delay deriving the `jit_return` address until `compile()`,
when the base pointer is available.

On railsbench, this yields roughly a 1% reduction to `yjit_alloc_size`
(58,397,765 to 57,742,248).

* YJIT: implement two-step call threshold

Automatically switch call threshold to a larger value for
larger, production-sized apps, while still allowing smaller apps
and command-line programs to start with a lower threshold.

* Update yjit/src/options.rs

Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

* Make the new variables constants

* Check that a custom call threshold was not specified

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Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>

Co-authored-by: Alan Wu <alansi.xingwu@shopify.com>

Previously, the version-controlled `cruby_bindings.inc.rs` file
contained the build-time artifact `id.h`, which nobu mentioned hinders
the goal of having fewer magic numbers in the repository.

Lookup the IDs YJIT needs on boot. It costs cycles, but it's fine since
YJIT only uses a handful of IDs at the moment. No perceptible
degradation to boot time found in my testing.

* Port call threshold logic from Rust to C for performance

* Prefix global/field names with yjit_

* Fix linker error

* Fix preprocessor condition for rb_yjit_threshold_hit

* Fix third linker issue

* Exclude yjit_calls_at_interv from RJIT bindgen

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Co-authored-by: Takashi Kokubun <takashikkbn@gmail.com>