The count of rb_alloc_tmp_buffer_with_count is the allocation size
counted in VALUE size but not in the requested element size.

Co-authored-by: Yusuke Endoh <mame@ruby-lang.org>
Co-authored-by: Koichi Sasada <ko1@atdot.net>

Deleted well over a decade ago in commit 977d66ec993b0f1892fb3e4cd8ac.

* Use the wrapper of rb_cObject instead of data access
* Replaced rest of extentions
* Updated the version guard for Data
* Added the version guard of rb_cData

Has been deprecated since 684bdf6171b76f5bc5e4f05926a5ab01ec2b4fd5.

Matz says in [ruby-core:83954] that Data should be an alias of Object.
Because rb_cData has not been deprecated, let us deprecate the constant
to make it a C-level synonym of rb_cObject.

It was my bad, the exception that actually raises is rb_eNoMemError.
[ci skip]

`@exception` is an alias of `@throw`.  It might suite Ruby's document
because ruby uses `raise` terminology instead of `throw`. [ci skip]

This adds rb_category_compile_warn in order to emit compiler warnings
with categories.  Note that Ripper currently ignores the category
for these warnings, but by default it ignores the warnings completely,
so this shouldn't matter.

Since we decided to only allowing specific warning categories,
there is no reason to have an API that accepts a general string,
as it is more error-prone.  Switch to only allowing the specific
warning categories.

As rb_category_warn{,ing} are public API, this requires making
rb_warning_category_t public API as well.

Deleted since fc3c60f6081d85f6274986a7a08b59db1515fcb5