Enumerator should use a non-blocking fiber, change `rb_fiber_new` to … #463

Job	Run time
make (yjit-bindgen, To fix: use patch in logs, --with-gcc=clang-12 --enable-yjit=dev)	3m 39s
make (check, RUSTC='rustc +1.58.0', 1.58.0)	17m 16s
cargo test	58s
make (check, --enable-yjit=dev)	24m 29s
cargo clippy	39s
make (check, --enable-yjit=dev, --yjit-call-threshold=1 --yjit-verify-ctx --yjit-code-gc)	27m 44s
make (test-bundled-gems, --enable-yjit=dev)	19m 6s
make (yjit-bench, --enable-yjit=dev, --yjit-stats, true)	5m 48s
YJIT Ubuntu result	1s
	1h 39m 40s

Provide feedback