inflate/bitreader: fix unsoundness in advance() #972

Job	Run time
QEMU build & test (stable, ubuntu-latest, s390x-unknown-linux-gnu, s390x-linux-gnu-gcc)	51s
QEMU build & test (stable, ubuntu-latest, i686-unknown-linux-gnu, i686-linux-gnu-gcc)	47s
Smoke-test fuzzing targets (default)	2m 40s
Clippy	19s
Smoke-test fuzzing targets (c-allocator)	2m 37s
Smoke-test fuzzing targets (stable, macos-14, aarch64-apple-darwin)	2m 39s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	56s
Smoke-test fuzzing targets (rust-allocator)	2m 36s
Clippy (--no-default-features --features="c-allocator")	16s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	56s
Clippy (--no-default-features --features="rust-allocator")	24s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	57s
dynamic library	20s
Miri	1m 36s
Build and test (stable, macos-latest, x86_64-apple-darwin)	1m 0s
Build and test (stable, macos-14, aarch64-apple-darwin)	59s
wasm32	52s
Build and test (stable-x86_64-gnu, windows-2022, x86_64-pc-windows-gnu)	2m 8s
	22m 53s

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