Fix underflow of `nbCompares` by switching to an `int` and comparing
`nbCompares > 0`. This is a minimal fix, because I don't want to change
the logic. These loops seem to be doing `nbCompares + 1` comparisons.

The bug was reported by Dan Carpenter and found by Smatch static
checker.

https://lore.kernel.org/all/20211008063704.GA5370@kili/

* Limit training samples size to 2GB

* simplified DISPLAYLEVEL() macro to use global vqriable instead of local.

* refactored training samples loading

* fixed compiler warning

* addressed comments from the pull request

* addressed @terrelln comments

* missed some fixes

* fixed type mismatch

* Fixed bug passing estimated number of samples rather insted of the loaded number of samples.
Changed unit conversion not to use bit-shifts.

* fixed a declaration after code

* fixed type conversion compile errors

* fixed more type castting

* fixed more type mismatching

* changed sizes type to size_t

* move type casting

* more type cast fixes

Add AIX support in Makefile

[contrib][linux-kernel] Add standard warnings and -Werror to CI

[contrib][linux] Fix -Wundef inside Linux kernel tree

add missing BUNDLE DESTINATION

Skip most long matches in lazy hash table update

fixes build on iOS

[huf] Fix OSS-Fuzz assert

Smaller code with disabled features

PR #2784 introduced a bug in the decompressor that caused some valid
inputs to fail to decompress. The bitstream isn't reloaded after the 4X*
loop if the number of elements remaining is small enough, causing us to
read more bits than are available in the bitcontainer.

This was caught by the MSAN fuzzer in OSS-Fuzz because the assembly
implementation isn't used in the MSAN build.

Credit to OSS-Fuzz.

provide correct reasons to include zstd_internal.h

Multiple ZSTD_createDCtx* functions call other (public)
ZSTD_createDCtx* functions, this makes it harder for humans
and compilers to throw out code that is not used.

This farms out the logic into a static function, if a program
only uses a single ZSTD_createDCtx variant, all others can be easily
dropped and the remaining implementation can be specialized.

Use an helper function, which will just return 0 in case
the feature is disabled.
Allows constant propagation and removal of dead code.

Remove the then unneeded variables from the struct,
and all accesses to them.

Commit d7ef97a0
("[build] Fix oss-fuzz build with the dataflow sanitizer") broke
build inside Linux-kernel after 'import', as it no longer can
conditionally remove ZSTD_MEMORY_SANITIZER definition from
the #if DEF_A || DEF_B block. This emits -Wundef warning which
can be treated as error.
Split this preprocessor condition into two separate conditions
to fix this.

Fixes: d7ef97a0 ("[build] Fix oss-fuzz build with the dataflow sanitizer")
Signed-off-by: Alexander Lobakin <alobakin@pm.me>

Test the kernel build with the standard warnings enabled so that we
don't miss issues like fixed in PR #2802.

Stacked on top of PR #2802 so CI passes, so it includes the fix. But, I
won't merge until it is merged, so @solbjorn gets the credit for the
fix.

[contrib][linux] Fix build after introducing ASM HUF implementation

[lib] Make lib compatible with `-Wfall-through` excepting legacy

[build] Fix oss-fuzz build with the dataflow sanitizer

Fix typo

The dataflow sanitizer requires all code to be instrumented. We can't
instrument the ASM function, so we have to disable it.

minor: constify MatchState* parameter when possible

Switch to a macro `ZSTD_FALLTHROUGH;` instead of a comment. On supported
compilers this uses an attribute, otherwise it becomes a comment.

This is necessary to be compatible with clang's `-Wfall-through`, and
gcc's `-Wfall-through=2` which don't support comments. Without this the
linux build emits a bunch of warnings.

Also add a test to CI to ensure that we don't regress.

turns out, it's possible to constify MatchState* parameter
in some parts of the binary tree algorithm,
making it a pure read-only parameter,
as opposed to a mutable state.

This is supposed to be helpful for both maintenance and the compiler.

The mentioned path is being created/used by the 'import' rule for
generating source files for Linux kernel.

Signed-off-by: Alexander Lobakin <alobakin@pm.me>

Commit a5f2c455 ("Huffman ASM") added a new ASM source file,
but it wasn't added to the kernel Makefile despite that it received
support for Huffman ASM according to the internal definitions. This
leads to undefined references, as huf_decompress.o now calls those
ASM functions.
Add it to the list of sources when building inside the kernel tree.
Kbuild can handle .S files just fine, so none additional rules
needed.

Fixes: a5f2c455 ("Huffman ASM")
Signed-off-by: Alexander Lobakin <alobakin@pm.me>

Linux 5.15 introduces a new Kconfig option, CONFIG_WERROR, which
forces -Werror for the entire kernel.
Current in-kernel ZSTD implementation uses functions deprecated
in 1.5.0, and thus fails on -Wdeprecated-declarations.
Turn this particular error into warning to be able to build the
kernel with CONFIG_WERROR. I'm not disabling them completely to
make sure they'll be visible and [hopefully] fixed sooner or later.

Signed-off-by: Alexander Lobakin <alobakin@pm.me>

Reduce stack usage of block splitter

[contrib][linux] Reduce stack usage by 80 bytes

Instead of calling `ZSTD_compress_advanced()` and
`ZSTD_initCStream_advanced()`, which each take a `ZSTD_parameters` by
value, use the new advanced API.

Stack usage went from 2024 -> 1944.

[contrib][linux] Fix up SPDX license identifiers