The cause is that `mrbgem.rake` of` mruby-test` gem is loaded when test
code is requested to be built, but when `mrbgem.rake` is loaded,
`MRuby::Gem.current` is updated, which is not thread safe.

Address this by not loading `mrbgem.rake` in parallel.

Remove functions for unimplemented methods

Integrate the argument parsing part of `IO.popen`

- Use `mrb_notimplement_m()` instead.
- Hide the unused `option_to_fd()` when `TARGET_OS_IPHONE` is enabled.

Add missing cast in `ea_next_capa_for`

Create a `mruby-config` that can be run on the host by cross-building

The output directory will be `host-bin`, so it will be output as `<build-dir>/host-bin/mruby-config`.

It's still not available for target devices.

Merge pull request #5281 from shuujii/remove-the-definition-of-mrb_uint-in-numeric.h-that-is-no-longer-needed

Remove the definition of `mrb_uint` in `numeric.h` that is no longer needed

Remove unneeded check to `mrbtest` in `tasks/presym.rake`

With the change in #5267, `build.products` no longer contains `mrbtest` when
`tasks/presym.rake` is loaded.

Remove unneeded `mruby-test` gem in `build_config/no-float.rb` [ci skip]

Use `enable_test` to enable the test.

Fix annotations [ci skip]

`1L` on Windows means `32 bit int`.

Fix build error in cross-build with presym

Replace `tempirep` with `RProc`

Fix the condition to remove `mrbtest` when `rake clean`

Previously I used the `RData` object to avoid a memory leak in `mrb_irep` if `src/load.c` failed.
ref: https://github.com/mruby/mruby/pull/4250
commit: f1523d24

Considering that the `RProc` object will be created in the subsequent process, it is preferable to create the `RProc` object from the beginning.
Along with this, the inside of `read_irep()` is replaced with the processing centered on the `RProc` object.

The global function that returns the `mrb_irep` pointer is still provided for compatibility.

This reverts commit 37d795de.
This reapplies e20d652f (#4202), which is reverted, but its issue was solved
by 1d8456fe.

Fix the following issues.

* https://github.com/mruby/mruby/pull/5220#issuecomment-757204258
* https://github.com/mruby/mruby/pull/5220#issuecomment-757205572

The first byte of UTF-8 character should not be `80..c1`.

Remove unnecessary `#include` in generated files

Reapply 116e128b because it is back at 456878ba

Delay test code build until `rake test`

`mrb_fiber_resume()` can be called from C; ref #3056

With this change, the test code will not be built unless `rake test` is
run, so there will be almost no side effects even if `enable_test` is
always set (but, gems specified by `add_test_dependency` are included
in `libmruby.a`).

Also added are `test: build` task, which only builds the test code
(including the main code), and `test: run` task, which only runs tests
independent of build. Therefore, the idiom for building in parallel and
not running tests in parallel is `rake -m test:build && rake test:run`.

Merge pull request #5266 from shuujii/stop-immediate-flush-to-stdout-stderr-when-running-in-parallel-on-CI

Stop immediate flush to stdout/stderr when running in parallel on CI

During parallel execution (build), it is sometimes flushed before line
breaks, and lines are concatenated.