Reorganize `mcall()` in `mruby-method`

According to CodeQL instruction, `HEAD^2` is no longer needed.

build(deps): bump actions/upload-artifact from v2.2.2 to v2.2.3

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from v2.2.2 to v2.2.3.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v2.2.2...ee69f02b3dfdecd58bb31b4d133da38ba6fe3700)
Signed-off-by: dependabot[bot] <support@github.com>

Updating dreamcast_shelf build configuration.

* `--cc` print compiler name
* `--ld` print linker name

Fix heading level in `doc/guides/link.md` [ci skip]

Fix typo in `doc/guides/link.md` [ci skip]

Making a proc object static for a method with static irep

The following methods will be made static.

  - `Class#new`
  - `Proc#call`
  - `Kernel#catch`

Previously, static const RProc could not be registered as a method, but this has been changed to allow it.

Use `mrb_exec_irep()`. If possible, re-entry into the VM will be suppressed.

Note that due to the effect of being a tail-call, the backtrace of `Method#call` will be lost, and it will look as if the target method was called directly.

This change fixes the problem of infinite loops when redefining methods that make block calls using `mruby-method`.

```console
% bin/mruby -e 'mm = method(:proc); define_method(:proc, ->(*a, &b) { mm.call(*a, &b) }); p proc { 1 }'
trace (most recent call last):
        [257] -e:1
        [256] -e:1:in proc
        [255] -e:1:in proc
        ...SNIP...
        [1] -e:1:in proc
-e:1:in proc: stack level too deep (SystemStackError)
```

Change the old `mrb_exec_irep()` as-is to static `mrb_exec_irep_vm()`.
Extract the VM entry part from the old `exec_irep()` in `mruby-eval/src/eval.c` and make it the core of the new `mrb_exec_irep()`.

Fix build failures with `enable_debug` and `enable_cxx_abi`

Fix the Authors link in the README

chore: fix spelling

Under C++, there is no implicit conversion from `int` to `enum`, which caused a compilation error.

Merge branch 'define-MRB_NO_GEMS-if-disable_libmruby-is-specified' of https://github.com/shuujii/mruby into shuujii-define-MRB_NO_GEMS-if-disable_libmruby-is-specified

Fix build with `MRB_USE_ALL_SYMBOLS`

- (old) `undefined method 'foo'`
- (new) `no superclass method 'foo'`

Add support for partial backtraces

When argument information is not available. So it should not happen for
`yield` (error). In contrast, the error from `super` should be handled
in run time (ignored).