rotate_right_1: special-case the 2-byte case

[folkertdev]

shows some good results for some of the benchmarks

Benchmark 2 (1588 runs): target/relwithdebinfo/examples/decompress rs tests/input/quick/sample1.bz2
  measurement          mean ± σ            min … max           outliers         delta
  wall_time          3.11ms ±  119us    2.85ms … 4.51ms         32 ( 2%)        ⚡-  1.5% ±  0.3%
  peak_rss           2.52MB ± 59.4KB    2.36MB … 2.62MB        395 (25%)          -  0.3% ±  0.2%
  cpu_cycles         9.31M  ±  208K     9.05M  … 13.1M          74 ( 5%)        ⚡-  1.8% ±  0.2%
  instructions       17.4M  ±  294      17.4M  … 17.4M          15 ( 1%)        ⚡-  7.8% ±  0.0%

Benchmark 2 (791 runs): target/relwithdebinfo/examples/decompress rs tests/input/quick/sample2.bz2
  measurement          mean ± σ            min … max           outliers         delta
  wall_time          6.29ms ±  186us    5.97ms … 9.05ms         31 ( 4%)        ⚡-  1.3% ±  0.3%
  peak_rss           3.05MB ± 60.3KB    2.88MB … 3.15MB          0 ( 0%)          -  0.1% ±  0.2%
  cpu_cycles         22.5M  ±  575K     22.1M  … 33.1M          58 ( 7%)        ⚡-  1.7% ±  0.2%
  instructions       39.2M  ±  279      39.2M  … 39.2M           6 ( 1%)        ⚡-  8.1% ±  0.0%

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Flag	Coverage Δ
fuzz-compress_then_decompress	51.08% <100.00%> (+0.08%)	⬆️
fuzz-decompress_chunked	30.03% <100.00%> (-1.46%)	⬇️
test-aarch64-apple-darwin	90.08% <100.00%> (+0.01%)	⬆️
test-x86_64-apple-darwin	90.18% <100.00%> (+0.01%)	⬆️
test-x86_64-unknown-linux-gnu	90.08% <100.00%> (+0.01%)	⬆️

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

Files with missing lines	Coverage Δ
libbz2-rs-sys/src/decompress.rs	96.60% <100.00%> (-1.28%)	⬇️

... and 1 file with indirect coverage changes

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