Do not pass ac when it is not needed #4636

Job	Run time
rustfmt-clippy	2m 19s
build-unix (beta-build)	4m 4s
build-unix (1.65.0-tests)	9m 30s
build-macos (Cargo build (x64), cargo-build, x86_64-apple-darwin)	4m 55s
build-windows (cargo-build, x86_64-pc-windows-msvc)	7m 45s
build-macos (Cargo test (x64), cargo-test, x86_64-apple-darwin)	8m 52s
build-unix (aom-tests)	8m 36s
build-windows (cargo-test, x86_64-pc-windows-msvc)	11m 45s
build-macos (Cargo C-build (x64), cargo-c, x86_64-apple-darwin)	8m 7s
build-unix (dav1d-tests)	7m 9s
build-windows (cargo-c, x86_64-pc-windows-gnu)	12m 55s
build-unix (no-asm-tests)	10m 27s
build-macos (Cargo build (Arm64), cargo-build, aarch64-apple-darwin)	4m 5s
build-unix (grcov-codecov)	12m 36s
build-macos (Cargo C-build (Arm64), cargo-c, aarch64-apple-darwin)	9m 13s
build-unix (bench)	4m 47s
build-unix (doc)	2m 39s
build-unix (cargo-c)	7m 4s
build-unix (check-no-default)	1m 50s
build-unix (check-extra-feats)	2m 59s
build-unix (check-unstable-feats)	2m 59s
build-unix (fuzz)	5m 10s
build-unix (dav1d-tests-arm64, stable)	10m 28s
	2h 40m 14s

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