Avoid using inconsistent coding style

	Other `_mjit_compile_*.erb` files don't use goto. These files'd better
	be consistent for readability.
	---
	 tool/ruby_vm/views/_mjit_compile_getinlinecache.erb | 14 +++-----------
	 1 file changed, 3 insertions(+), 11 deletions(-)

	Fix broken JIT of getinlinecache

	e7fc353f04 reverted vm_ic_hit_p's signature change made in 53babf35ef,
	which broke JIT compilation of getinlinecache.

	To make sure it doesn't happen again, I separated vm_inlined_ic_hit_p to
	make the intention clear.
	---
	 test/ruby/test_jit.rb                              | 12 +++++++++++
	 .../ruby_vm/views/_mjit_compile_getinlinecache.erb |  2 +-
	 vm_insnhelper.c                                    | 25 ++++++++++++++--------
	 3 files changed, 29 insertions(+), 10 deletions(-)

constant cache `IC` is accessed by non-atomic manner and there are
thread-safety issues, so Ruby 3.0 disables to use const cache on
non-main ractors.

This patch enables it by introducing `imemo_constcache` and allocates
it by every re-fill of const cache like `imemo_callcache`.
[Bug #17510]

Now `IC` only has one entry `IC::entry` and it points to
`iseq_inline_constant_cache_entry`, managed by T_IMEMO object.

`IC` is atomic data structure so `rb_mjit_before_vm_ic_update()` and
`rb_mjit_after_vm_ic_update()` is not needed.

* Inline getconstant on JIT

* Support USE_MJIT=0