object_id of true, false, and undef are all 0

Should not free the pointer in `realloc` since it can cause
use-after-free problem.

Work around MSC optimization generating non functional code with Array#shuffle

The bug was introduced by 9dfe50f1.

The POSIX `realloc` keep the original pointer untouched, so it can
easily leads to memory leakage. `mrb_realloc()` should handle those
bookkeeping, while `mrb_realloc_simple()` keeps the original `realloc`
behavior.

Use simpler `mrb_get_argc()` and `mrb_get_arg1()` instead.

C implementation used `mrb_funcall()` that bypassed many optimization.

`mrb_get_arg1()` raises `ArgumentError` if the method does not receive one
argument.

And replaces all `mrb_get_args(mrb, "o", &arg)` by the new function.

Since we made our opcode byte based, we need no endian option (`-e`
and `-E`) to `mrbc`.

Remove `mrb_assert()` in `Module.nesting`

Need `build/XXX/mrbgems/mruby-test` directory

Update `test/t/kernel.rb`