inout: use `core::ptr::eq` (#1175) #1820

Job	Run time
build (stable, thumbv7em-none-eabi)	11s
test (1.85.0)	19s
build (1.85.0, thumbv7em-none-eabi)	16s
build (stable, wasm32-unknown-unknown)	8s
test (stable)	12s
build (1.85.0, wasm32-unknown-unknown)	19s
minimal-versions / minimal-versions	26s
	1m 51s

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