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

--- a/contrib/python-zstandard/setup.py	Sat Apr 01 13:43:52 2017 -0700
+++ b/contrib/python-zstandard/setup.py	Sat Apr 01 15:24:03 2017 -0700
@@ -25,10 +25,15 @@
 # facilitate reuse in other projects.
 extensions = [setup_zstd.get_c_extension(SUPPORT_LEGACY, 'zstd')]
 
+install_requires = []
+
 if cffi:
     import make_cffi
     extensions.append(make_cffi.ffi.distutils_extension())
 
+    # Need change in 1.8 for ffi.from_buffer() behavior.
+    install_requires.append('cffi>=1.8')
+
 version = None
 
 with open('c-ext/python-zstandard.h', 'r') as fh:
@@ -67,4 +72,5 @@
     keywords='zstandard zstd compression',
     ext_modules=extensions,
     test_suite='tests',
+    install_requires=install_requires,
 )