Display command line parameters with concrete values in verbose mode

ZSTD_copy16() uses ZSTD_memcpy()

Fix Determinism Bug: Avoid Reducing Indices to Reserved Values

Previously, if an index was equal to `reducerValue + 1`, it would get remapped
during index reduction to 1 i.e. `ZSTD_DUBT_UNSORTED_MARK`. This can affect the
parsing of the input slightly, by causing tree nodes to be nullified when they
otherwise wouldn't be. This hardly matters from a correctness or efficiency
perspective, but it does impact determinism.

So this commit changes index reduction to avoid mapping indices to collide with
`ZSTD_DUBT_UNSORTED_MARK`.

Backport zstd patch from LKML

Credit to Nathan Chancellor for the bug fix and Nick Desaulniers for the
bug report.

Link: https://github.com/ClangBuiltLinux/linux/issues/1486
Link: https://lore.kernel.org/all/20211021202353.2356400-1-nathan@kernel.org/

Use unused functions to appease Visual Studio

Improvements to verbose mode output - decompression memory usage

This accelerates the decompression speed of MSVC build.

minor : change build macro to ZSTD_DECODER_INTERNAL_BUFFER

also : introduced macro BOUNDED()

separate compression level tables into their own file

[lazy] Speed up compilation times

that's clearer than finding the tables somewhere in the middle of `compress.c`.

Also, down the line, it may potentially allows zstd to feature adjusted tables depending on target cpu.

just to make the topic more accessible for potential users.

* Reduce size of dctx by reutilizing dst buffer

Co-authored-by: Binh Vo <binhvo@fb.com>

Support thread pool section in HTML documentation.

Speed up compilation times by moving each specialized search function
into its own function. This is faster because compilers can handle many
smaller functions much faster than one gigantic function. The previous
approach generated one giant function with `switch` statements and
inlining to select the implementation.

| Compiler | Flags                               | Dev Time (s) | PR Time (s) | Delta |
|----------|-------------------------------------|--------------|-------------|-------|
| gcc      | -O3                                 |         16.5 |         5.6 |  -66% |
| gcc      | -O3 -g -fsanitize=address,undefined |        158.9 |        38.2 |  -75% |
| clang    | -O3                                 |         36.5 |         5.5 |  -85% |
| clang    | -O3 -g -fsanitize=address,undefined |         27.8 |        17.5 |  -37% |

This also reduces the binary size because the search functions are no
longer inlined into the main body.

| Compiler | Dev libzstd.a Size (B) | PR libzstd.a Size (B) | Delta |
|----------|------------------------|-----------------------|-------|
| gcc      |                1563868 |               1308844 |  -16% |
| clang    |                1924372 |               1376020 |  -28% |

Finally, the performance is not impacted significantly by this change,
in fact we generally see a small speed boost.

| Compiler | Level | Dev Speed (MB/s) | PR Speed (MB/s) | Delta |
|----------|-------|------------------|-----------------|-------|
| gcc      |     5 |            110.6 |           110.0 | -0.5% |
| gcc      |     7 |             70.4 |            72.2 | +2.5% |
| gcc      |     9 |             53.2 |            53.5 | +0.5% |
| gcc      |    13 |             12.7 |            12.9 | +1.5% |
| clang    |     5 |            113.9 |           110.4 | -3.0% |
| clang    |     7 |             67.7 |            70.6 | +4.2% |
| clang    |     9 |             51.9 |            52.2 | +0.5% |
| clang    |    13 |             12.4 |            13.3 | +7.2% |

The compression strategy is unmodified in this PR, so the compressed size
should be exactly the same. I may have a follow up PR to slightly improve
the compression ratio, if it doesn't cost too much speed.

[asm] Switch to C style comments

Switch to C style comments for increased portability, and consistency.

Fix a C89 error in msvc

Pipelined Implementation of ZSTD_dfast