[PATCH] [Bug #21629] Enable `nonstring` attribute on clang 21

	[PATCH] [Bug #21629] Initialize `struct RString`

	[PATCH] [Bug #21629] Initialize `struct RArray`

	Fix Exception#detailed_message for GC compaction

	Before this commit, the test fails with RGENGC_CHECK_MODE enabled:

	    TestException#test_detailed_message_under_gc_compact_stress [test/ruby/test_exception.rb:1466]:
	    <"\e[1mfoo (\e[1;4mRuntimeError\e[m\e[1m)\e[m\n" +
	    "\e[1mbar\e[m\n" +
	    "\e[1mbaz\e[m"> expected but was
	    <"\e[1mfoo (\e[1;4mRuntimeError\e[m\e[1m)\e[m\n" +
	    "\e[1m\x00\x00\x00\x00\x00\x00\x00\e[m">.

Don't call `Warning.warn` unless the category is enabled

The warning category should be enabled if we want to call
`Warning.warn`.

This commit speeds up the following benchmark:

```ruby
eval "def test; " +
  1000.times.map { "'  '.chomp!" }.join(";") + "; end"

def run_benchmark count
  i = 0
  while i < count
    start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    yield
    ms = Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
    puts "itr ##{i}: #{(ms * 1000).to_i}ms"
    i += 1
  end
end

run_benchmark(25) do
  250.times do
    test
  end
end
```

On `master` this runs at about 92ms per iteration. With this patch, it
is 7ms per iteration.

[Bug #20573]

Fix NoMethodError example of rendering

`die()` calls `abort()` which always exit as it `SIGABRT`
was received.

This isn't very friendly with systems that automatically
collect crashes as the `%s` parameter will be changed.

Mostly just fixing RDoc's incorrect treatment of `+`

when the RUBY_FREE_ON_SHUTDOWN environment variable is set, manually free memory at shutdown.

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
Co-authored-by: Peter Zhu <peter@peterzhu.ca>

For this public API, the callback is declared to take
`(ID, VALUE, st_data_t)`, but it so happens that using
`(st_data_t, st_data_t, st_data_t)` also
type checks, because the underlying type is identical.
Use it as declared and get rid of some casts.

These aren't particularly common, but avoiding the malloc churn
for small types is always nice, and this commit also modernize
and cleanup the TypedData API usage.

This commit adds a new flag RUBY_TYPED_EMBEDDABLE that allows the data
of a TypedData object to be embedded after the object itself. This will
improve cache locality and allow us to save the 8 byte data pointer.

Co-Authored-By: Jean Boussier <byroot@ruby-lang.org>