* See [Feature #17752]

Co-authored-by: xtkoba (Tee KOBAYASHI) <xtkoba+ruby@gmail.com>

I'm not necessarily against every goto in general, but jumping into a
branch is definitely a bad idea.  Better refactor.

On USE_LAZY_LOAD=1, the iseq should be loaded. So rb_iseq_check()
is needed. Furthermore, now lazy loading with builtin_function_table
is not supported, so it should cancel lazy loading.

`builtin_binary` is sorted by miniruby loading order and this
loading order should be same on ruby. So we can believe sorted
order of `builtin_binary` on boot time.

On cross-compilation, compiled binary can no be created because
compiled binary should be created by same interpreter (on cross-
compilation, host ruby is used to build ruby (BASERUBY)).
So that cross-compilation system loads required scripts in text.
It is same as miniruby.

`gem_prelude.rb` is not compiled yet. This patch compile it to
compiled binary.

rb_vm_lvar_exposed() is prepared for __builtin_inline!(), needed for
mini_builtin.c and builtin.c. However, it's only on builtin.c.
So move it to make it as a part of VM.

Add an experimental `__builtin_inline!(c_expression)` special intrinsic
which run a C code snippet.
In `c_expression`, you can access the following variables:
  * ec (rb_execution_context_t *)
  * self (const VALUE)
  * local variables (const VALUE)
Not that you can read these variables, but you can not write them.
You need to return from this expression and return value will be a
result of __builtin_inline!().

Examples:
  `def foo(x) __builtin_inline!('return rb_p(x);'); end` calls `p(x)`.
  `def double(x) __builtin_inline!('return INT2NUM(NUM2INT(x) * 2);')`
  returns x*2.

This reverts commit dfac2e9eb3d697e56d91151584f1d3cf9d2c79c9.

It does not work if cwd is different from builddir...