shape.h: remove YJIT workaround #281

Job	Run time
cargo test	1m 9s
make (check, --enable-yjit, --yjit)	6m 55s
make (check, --enable-yjit=dev, --yjit-call-threshold=1 --yjit-verify-ctx --yjit-code-gc, -T --yj...	16m 26s
YJIT macOS Arm64 result	4s
	24m 34s

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