Port of stb_image optimized paeth unfiltering #621

Job	Run time
rustfmt	16s
powerpc_cross	9s
build (1.57.0, ubuntu-latest)	50s
feature_check	1m 0s
build (1.57.0, windows-latest)	1m 13s
test_all	3m 12s
feature_check (benchmarks)	58s
build (1.57.0, macos-latest)	1m 5s
build (stable, ubuntu-latest)	13s
build (stable, windows-latest)	45s
build (stable, macos-latest)	16s
build (beta, ubuntu-latest)	11s
build (beta, windows-latest)	40s
build (beta, macos-latest)	17s
build (nightly, ubuntu-latest)	14s
build (nightly, windows-latest)	26s
build (nightly, macos-latest)	17s
	12m 2s

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