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.

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).

mrbc: Dump debug info with -g option

Adds debug source information (line/file) when mrbc uses -g.
This commit results in usable backtraces for all gems when build_config
is setup with enable_debug.