Dictionaries are prebuilt and saved as part of the data object.
The config decides whether or not to use the dictionary if it is
available. Configs that require dictionaries are only run with
data that have dictionaries. The method will skip configs that are
irrelevant, so for example ZSTD_compress() will skip configs with
dictionaries.

I've also trimmed the silesia source to 1MB per file (12 MB total),
and added 500 samples from the github data set with a dictionary.

I've intentionally added an extra line to the `results.csv` to make
the nightly build fail, so that we can see how CircleCI reports it.

Full list of changes:

* Add pre-built dictionaries to the data.
* Add `use_dictionary` and `no_pledged_src_size` flags to the config.
* Add a config using a dictionary for every level.
* Add a config that specifies no pledged source size.
* Support dictionaries and streaming in the `zstdcli` method.
* Add a context-reuse method using `ZSTD_compressCCtx()`.
* Clean up the formatting of the `results.csv` file to align columns.
* Add `--data`, `--config`, and `--method` flags to constrain each
  to a particular value. This is useful for debugging a failure
  or debugging a particular config/method/data.

Small changes for buck build

[regression] Add initial regression test framework

The regression tests run nightly or on the `regression`
branch for convenience. The results get uploaded as the
artifacts of the job. If they change, check the diff
printed in the job. If all is well, download the new
results and commit them to the repo.

This code will only run on a UNIX like platform. It
could be made to run on Windows, but I don't think that
it is necessary. It also uses C99.

* data: This module defines the data to run tests on.
  It downloads data from a URL into a cache directory,
  checks it against a checksum, and unpacks it. It also
  provides helpers for accessing the data.
* config: This module defines the configs to run tests
  with. A config is a set of API parameters and a set of
  CLI flags.
* result: This module is a helper for method that defines
  the result type.
* method: This module defines the compression methods
  to test. It is what runs the regression test using the
  data and the config. It reports the total compressed
  size, or an error/skip.
* test: This is the test binary that runs the tests for
  every (data, config, method) tuple, and prints the
  results to the output file and stderr.
* results.csv: The results that the current commit is
  expected to produce.

Fix  #1428 - zstdgrep now returns 1 on unmatch

fixed a typo

Update meson build system

NOTE: This commit only tested on Linux (Ubuntu 18.04). Windows
build may not work as expected.

* Use meson >= 0.47.0 cause we use install_man function
* Add three helper Python script:
  * CopyFile.py: To copy file
  * CreateSymlink.py: To make symlink (both Windows and Unix)
  * GetZstdLibraryVersion.py: Parse lib/zstd.h to get zstd version
  These help emulating equivalent functions in CMake and Makefile.
* Use subdir from meson to split meson.build
  * Add contrib build
  * Fix other build
* Add new build options
  * build_programs: Enable programs build
  * build_contrib: Enable contrib build
  * build_tests: Enable tests build
  * use_static_runtime: Link to static run-time libraries on MSVC
  * zlib_support: Enable zlib support
  * lzma_support: Enable lzma support

Fix feature detection with multiple -arch flags

Fix i386 build failure "Junk character 13"

When multiple -arch flags are used, the compiler invokes itself once for
each architecture. Apparently, input on stdin is consumed by the
compilation of the first arch and is no longer available to the
compilation of the second arch, which results in a build failure and the
potentially incorrect determination that a feature is not available. So
write the feature detection source to a file instead of using stdin.

- Factor out LDM's hash function for reuse
- Add rsyncable mode to zstdmt and expose it via the advanced API
- Fix `-B`/`--block-size` to actually set the job size
- Add rsyncable tests to `zstreamtest` and `playTests.sh`

Tested by:

```
> cat A.100MB B.100MB C.100MB D.100MB E.100MB | zstd --rsyncable -fo src/file.zst
/*stdin*\            : 48.22%   (524288000 => 252837782 bytes, src/file.zst)
> rsync -rc --stats src devbigvm:/data/users/terrelln/rsync-test
Total bytes sent: 252868779
total size is 252837782  speedup is 1.00
> echo test > test
> cat test A.100MB test B.100MB test C.100MB test D.100MB test E.100MB | zstd --rsyncable -fo src/file.zst
/*stdin*\            : 48.23%   (524288025 => 252838025 bytes, src/unicorn.tar.zst)
> rsync -rc --stats src devbigvm:/data/users/terrelln/rsync-test
Total bytes sent: 4605696
total size is 252838025  speedup is 53.60
```

Close #1155.

- Add rsyncable mode to multithreaded mode
- Factor out LDM's hash function for reuse

Separating benchfn and benchzstd

because gcc considers that
`void* const *`  and `void**` are 2 different types ...

to use structure for function parameters
as it expresses much clearer than a long list of parameters,
since each parameter can now be named.

with BMK_extract_returnValue()

it shall be possible to use benchfn
without any dependency on zstd.

Fix #1412: Perform Signed Comparison When Setting Attach Dict Param

which is more accurate