[fuzz] Add Huffman round trip fuzzer

[fuzz] Add Huffman round trip fuzzer

* Add a Huffman round trip fuzzer
* Fix two minor bugs in Huffman that aren't exposed in zstd
  - Incorrect weight comparison (weights are allowed to be equal to
    table log).
  - HUF_compress1X_usingCTable_internal() can return compressed
    size >= source size, so the assert that `cSize <= 65535` isn't
    correct, and it needs to be checked instead.