add minor huf encode / decode performance optimizations #2321

Job	Run time
Linux.1: Release / steps	13m 42s
Linux.2: Debug / steps	23m 52s
Linux.3: static / steps	13m 52s
Linux.4: threads=OFF / steps	12m 54s
Linux.6: custom namespace / steps	13m 46s
Linux.5: pkgconfig=OFF, examples=OFF, tools=OFF, docs=OFF, internal deflate / steps	4m 8s
Linux.7: clang / steps	14m 2s
Linux.8: vfx2023 / steps	12m 28s
macOS.1: Release / steps	8m 48s
macOS.2: Debug / steps	18m 23s
macOS.3: static / steps	7m 28s
macOS.4: threads=OFF / steps	8m 6s
macOS.5: pkgconfig=OFF, examples=OFF, tools=OFF, docs=OFF, internal imath+deflate / steps	1m 8s
macOS.6: macos-13 / steps	20m 50s
Windows.1: Release / steps	13m 4s
Windows.2: Debug / steps	39m 25s
Windows.3: static / steps	12m 53s
Windows.4: threads=OFF / steps	13m 25s
Windows.5: pkgconfig=OFF, examples=OFF, tools=OFF, docs=OFF, internal imath+deflate / steps	2m 22s
Windows.6: vfx2022 / steps	13m 46s
	4h 28m 22s

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