WIP freebsd: fix sysroot layout #4044

Job	Run time
check	25s
cargo-deny	24s
clippy (macos-latest)	52s
fmt	8s
clippy (ubuntu-latest)	21s
clippy (windows-latest)	57s
generate-matrix	21s
shellcheck	10s
test (macos-latest)	1m 42s
test (ubuntu-latest)	1m 11s
test (windows-latest)	2m 57s
foreign	3m 12s
remote	2m 13s
bisect	4m 38s
docker-in-docker	4m 5s
podman	2m 8s
target (${{ matrix.pretty }},${{ matrix.os }})	0s
publish	0s
conclusion	1s
Coverage	13s
	25m 58s

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