v1.4.9
[trace] Minor fixes found during integration
[bug-fix] Make simple single-pass functions ignore advanced parameters
[trace] Keep track of a uint64_t tracing context
[license] Update year to 2021
fixed minor cast warning
makes it possible to compile libzstd in single-thread mode without zstdmt_compress.c (#819)
Fix buck for lib
Use standard md5 tool on NetBSD.
updated build documentation
Avoid Use of Regexes in Building Package-Config File
Bump Library Version 1.4.8 -> 1.4.9