Tests for (`Float` or `Integer`) `op` `Rational`.

It removes non-static function, so that strictly saying, it's
an incompatible change. But the function was added recently and I am
sure no one uses it yet.

This function takes `struct mrb_rational*` and returns converted
`mrb_float` value.

This change relies that `mrb_num_div_flo` does not use `mrb` inside.

This function handles zero division properly. Also fixed bugs that multiply
numbers instead of division.

Use `NaN*i` as CRuby does.

Use global defines for `mruby-bin-debugger`

Reorganize types for `ObjectSpace.count_objects`

#### Addition

- T_COMPLEX
- T_RATIONAL

#### Deletion

- T_FALSE
- T_FREE
- T_TRUE
- T_SYMBOL
- T_UNDEF

Add example for cross-compiling to Nintendo Switch

Add configuration for MinGW cross compilation [ci skip]

along with repeated calls of `strlen()`.

Cross Compiling configuration for the Nintendo Switch, it requires Nintendo SDK

With this cross compiler configuration, all tests for full-core gembox on
Windows on GitHub Actions were successful.

This change also fixes the error caused by `rational.c` that calls
`mrb_complex_eq()`, which had been undefined.

`MRB_INT_MIN` does not have a corresponding positive value.

- define `MRB_TT_COMPLEX`
- change object structure (`struct RComplex`)
- add memory management for `MRB_TT_COMPLEX`
- avoid operator overloading as much as possible
- as a result, performance improved a log
- should work with and without `Rational` defined