nt32|nt64: abi upgrade: properly support NTFS directory entries.
    
    Following musl commit 614c9e7b1eecb71c5718c34f1724e8758cbe3c27, it is
    now possible to support NTFS directory entries consisting of 255 utf-16
    characters of the (little-endian) form zzzzyyyy yyxxxxxx, of which the
    respective utf-8 representation form is 1110zzzz  10yyyyyy  10xxxxxx.
    
    Paired with psxscl commit 26192ddd4a7b9100f97825982697d8a918563fe9,
    and introduces a pre-alpha abi upgrade.