merge revision(s) 015b0e2e,ac1e9e44: [Backport #20195]

	YJIT: Fix unused warnings

	```
	warning: unused import: `condition::Condition`
	  --> src/asm/arm64/arg/mod.rs:13:9
	   |
	13 | pub use condition::Condition;
	   |         ^^^^^^^^^^^^^^^^^^^^
	   |
	   = note: `#[warn(unused_imports)]` on by default

	warning: unused import: `rb_yjit_fix_mul_fix as rb_fix_mul_fix`
	   --> src/cruby.rs:188:9
	    |
	188 | pub use rb_yjit_fix_mul_fix as rb_fix_mul_fix;
	    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	warning: unused import: `rb_insn_len as raw_insn_len`
	   --> src/cruby.rs:142:9
	    |
	142 | pub use rb_insn_len as raw_insn_len;
	    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
	    |
	    = note: `#[warn(unused_imports)]` on by default
	```

	Make asm public so it stops warning about unused public stuff in there.

	YJIT: Fix ruby2_keywords splat+rest and drop bogus checks

	YJIT didn't guard for ruby2_keywords hash in case of splat calls that
	land in methods with a rest parameter, creating incorrect results.

	The compile-time checks didn't correspond to any actual effects of
	ruby2_keywords, so it was masking this bug and YJIT was needlessly
	refusing to compile some code. About 16% of fallback reasons in
	`lobsters` was due to the ISeq check.

	We already handle the tagging part with
	exit_if_supplying_kw_and_has_no_kw() and should now have a dynamic guard
	for all splat cases.

	Note for backporting: You also need 7f51959f.

	[Bug #20195]