Merge branch 'mrb_debug_strdup-and-strndup' of https://github.com/cremno/mruby into cremno-mrb_debug_strdup-and-strndup

To be compatible with CRuby.

- `Lit` -> `Pool`
- `SEQ` -> `Irep`

The code generator no longer need to emit `OP_LOADSYM` after `OP_DEF`.
`doc/opcode.md` is also updated.

This reverts commit fd10c723.

I thought it was OK to restrict index value within 1 byte, but in some
cases index value could be 16 bits (2 bytes). I had several ideas to
address the issue, but reverting `fd10c723` is the easiest way. The
biggest reason is `mruby/c` still supports `OP_EXT[123]`, so that they
don't need any additional work.

Drop unnecessary upper procs linked from class/module/def syntax

Avoid warnings with `ruby -cw`

```console
% for rb in `git ls-files '*/mrblib/*.rb' 'mrblib'`; do ruby30 -cw $rb > /dev/null; done
mrbgems/mruby-array-ext/mrblib/array.rb:389: warning: assigned but unused variable - ary
mrbgems/mruby-array-ext/mrblib/array.rb:663: warning: assigned but unused variable - len
mrbgems/mruby-hash-ext/mrblib/hash.rb:119: warning: possibly useless use of a variable in void context
mrbgems/mruby-hash-ext/mrblib/hash.rb:259: warning: assigned but unused variable - keys
mrbgems/mruby-io/mrblib/io.rb:229: warning: literal in condition
mrbgems/mruby-io/mrblib/io.rb:280: warning: literal in condition
mrbgems/mruby-string-ext/mrblib/string.rb:347: warning: assigned but unused variable - len
mrbgems/mruby-toplevel-ext/mrblib/toplevel.rb:2: warning: parentheses after method name is interpreted as an argument list, not a decomposed argument
```

It does not need to hold an anonymous proc for constant search.
Also, this change can be expected to cause an anonymous proc to be GC'd.

This is useful for metaprogramming that makes heavy use of the `class`/`module`/`def` syntax in the `class_eval`/`eval` method.

Example:

- code

  ```ruby
  p ObjectSpace.count_objects

  String.class_eval do
    def a
    end
  end

  p ObjectSpace.count_objects

  String.class_eval do
    eval <<~CODE
      def b
      end
    CODE
  end

  p ObjectSpace.count_objects
  ```

- result of building mruby-head (d63c0df6) with `build_config/default.rb`

  ```
  {:TOTAL=>1024, :FREE=>262, :T_PROC=>495, :T_ENV=>61, ...}
  {:TOTAL=>1024, :FREE=>259, :T_PROC=>497, :T_ENV=>62, ...}
  {:TOTAL=>1024, :FREE=>255, :T_PROC=>500, :T_ENV=>63, ...}
  ```

- result of building mruby with this patch and `build_config/default.rb`

  ```
  {:TOTAL=>1024, :FREE=>264, :T_PROC=>494, :T_ENV=>60, ...}
  {:TOTAL=>1024, :FREE=>262, :T_PROC=>495, :T_ENV=>61, ...}
  {:TOTAL=>1024, :FREE=>261, :T_PROC=>496, :T_ENV=>61, ...}
  ```

Fixed finding variables from `proc` in `binding.eval` failed

Fixed finding variables defined in the upper proc failed

Previously the following code did not produce the expected results:
```ruby
bx = binding
block = bx.eval("a = 1; proc { a }")
bx.eval("a = 2")
p block.call  # Expect 2 but return 1 due to a bug
```

The previous implementation of `Binding#eval` evaluated the code and then merged the top layer variables.
This patch will parse and expand the variable space before making a call to `eval`.
This means that the call to `Binding#eval` will do the parsing twice.

In addition, the following changes will be made:
- Make `mrb_parser_foreach_top_variable()`, `mrb_binding_extract_proc()` and `mrb_binding_extract_env()` functions private global functions.
- Remove the `posthook` argument from `mrb_exec_irep()`.
  The `posthook` argument was introduced to implement the `binding` method.
  This patch is unnecessary because it uses a different implementation method.

ref #5362
fixed #5491

Fix memory leak in `Kernel#eval`

If no new variable was defined in the `eval` method, the variable was hidden from the nested `eval` method.

```ruby
a = 1
p eval %(b = 2; eval %(a)) # => 1 (good)
p eval %(eval %(a)) # => undefined method 'a' (NoMethodError)
```

This issue has occurred since mruby 3.0.0.

The `mrbc_context` remained unreleased when the `mrb_parse_nstring()` function returned `NULL`.

- `Module#method_added`
- `BasicObject#singleton_method_added`

Add official pre-commit file-contents-sorter

Remove unneeded bash script sort-codespell-wordlist.sh

https://github.com/pre-commit/pre-commit-hooks#file-contents-sorter

* android_arm64-v8a.rb -> android_arm64_v8a.rb
* no-float.rb -> host-nofloat.rb

Enable markdownlint rules MD003,MD005,MD007

pre-commit autoupdate

https://pre-commit.com/#pre-commit-autoupdate

Lint Markdown

https://github.com/DavidAnson/markdownlint#rules--aliases

- `truncate`
- `floor`
- `ceil`

`round` already takes `ndigits`.

Added `MRB_OBJ_ALLOC()` macro that does not require a cast

The `MRB_OBJ_ALLOC()` macro function returns a pointer of the type corresponding to the constant literal defined in `enum mrb_vtype`.

- ` mrb_block_given_p()` -- The name comes from CRuby's `rb_block_given_p ()`

At the same time, it applies to `f_instance_eval()` and `f_class_eval()` of `mruby-eval`.