Simplify freelist management logic #886

Job	Run time
build-solaris / cross-build (amd64)	25s
build-linux / cross-build (loong64)	25s
build-linux / cross-build (ppc64)	10s
build-linux / cross-build (mipsle)	23s
build-linux / cross-build (mips)	17s
build-linux / cross-build (arm64)	27s
build-linux / cross-build (ppc64le)	22s
build-linux / cross-build (arm)	24s
build-windows / cross-build (arm64)	24s
build-linux / cross-build (mips64)	25s
build-linux / cross-build (386)	23s
build-openbsd / cross-build (amd64)	21s
build-openbsd / cross-build (arm)	23s
build-windows / cross-build (386)	30s
build-linux / cross-build (s390x)	29s
build-aix / cross-build (ppc64)	21s
build-linux / cross-build (mips64le)	22s
build-openbsd / cross-build (ppc64)	23s
build-android / cross-build (arm64)	27s
build-windows / cross-build (amd64)	25s
build-openbsd / cross-build (arm64)	24s
build-openbsd / cross-build (riscv64)	26s
build-linux / cross-build (riscv64)	24s
build-openbsd / cross-build (386)	30s
build-linux / cross-build (amd64)	26s
	9m 56s

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