zstd: vendor python-zstandard 0.8.0
Commit
81e1f5bbf1fc54808649562d3ed829730765c540 from
https://github.com/indygreg/python-zstandard is imported without
modifications (other than removing unwanted files).
Updates relevant to Mercurial include:
* Support for multi-threaded compression (we can use this for
bundle and wire protocol compression).
* APIs for batch compression and decompression operations using
multiple threads and optimal memory allocation mechanism. (Can
be useful for revlog perf improvements.)
* A ``BufferWithSegments`` type that models a single memory buffer
containing N discrete items of known lengths. This type can be
used for very efficient 0-copy data operations.
# no-check-commit
<entry>
<title>{bookmark|escape}</title>
<link rel="alternate" href="{urlbase}{url|urlescape}rev/{node|short}"/>
<id>{urlbase}{url|urlescape}#bookmark-{node}</id>
<updated>{date|rfc3339date}</updated>
<published>{date|rfc3339date}</published>
<content type="text">{bookmark|strip|escape}</content>
</entry>