Ignore unused variables on iOS #12412

Job	Run time
android	19s
Check wasm32 + wasm-bindgen	2m 32s
Format + check + test	5m 31s
cargo-deny aarch64-apple-darwin	37s
ios	34s
cargo-deny aarch64-linux-android	41s
Check Windows	1m 39s
cargo-deny i686-pc-windows-gnu	40s
cargo-deny i686-pc-windows-msvc	38s
cargo-deny i686-unknown-linux-gnu	39s
cargo-deny wasm32-unknown-unknown	39s
cargo-deny x86_64-apple-darwin	40s
cargo-deny x86_64-pc-windows-gnu	38s
cargo-deny x86_64-pc-windows-msvc	41s
cargo-deny x86_64-unknown-linux-gnu	40s
cargo-deny x86_64-unknown-linux-musl	39s
cargo-deny x86_64-unknown-redox	37s
	18m 24s

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