`bzip2.rs`: remove final `fprintf` usage #150

Job	Run time
Clippy	13s
QEMU build & test (stable, ubuntu-latest, s390x-unknown-linux-gnu, s390x-linux-gnu-gcc, qemu-s390...	38s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	56s
Clippy (--no-default-features --features="c-allocator")	9s
QEMU build & test (stable, ubuntu-latest, i686-unknown-linux-gnu, i686-linux-gnu-gcc)	42s
Miri	1m 10s
Build and test (msrv, ubuntu-latest, x86_64-unknown-linux-gnu)	35s
Clippy (--no-default-features --features="rust-allocator")	23s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	34s
wasm32	29s
	5m 49s

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