a slice fill is now turned into a memset even when using miri

[folkertdev]

The fix from rust-lang/rust#147457 should resolve the slow runtimes we were seeing.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
fuzz-compress	40.49% <100.00%> (-0.04%)	⬇️
fuzz-decompress	30.42% <0.00%> (-0.26%)	⬇️
test-aarch64-apple-darwin	92.26% <100.00%> (-0.05%)	⬇️
test-aarch64-unknown-linux-gnu	89.70% <100.00%> (-0.04%)	⬇️
test-i686-unknown-linux-gnu	89.47% <100.00%> (-0.05%)	⬇️
test-x86_64-apple-darwin	91.57% <100.00%> (-0.04%)	⬇️
test-x86_64-unknown-linux-gnu	92.26% <100.00%> (-0.09%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
zlib-rs/src/deflate.rs	96.50% <100.00%> (-0.09%)	⬇️
zlib-rs/src/deflate/sym_buf.rs	96.00% <100.00%> (ø)
zlib-rs/src/lib.rs	94.33% <ø> (ø)

... and 2 files with indirect coverage changes

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[folkertdev]

Maybe there is a slight (10s) increase? Anyway, I'd rather get rid of the code in this case.