Integrate build system support for the Zstandard (zstd) library and
implement the corresponding C++ decompression stream classes, enabling
future use of zstd-compressed streams in ZIP packages.
Build System (Part 2a):
- Add `--with-system-zstd=[yes|no|auto]` configure option.
- Implement system library checks (`zstd.h`, `libzstd`) in configure.ac.
- Define rules (`external/zstd/*`) for downloading and building the
internal zstd static library (decompression components only).
- Set up necessary CFLAGS/LIBS via configure.ac and config_host.mk.in.
- Configure linking via RepositoryExternal.mk (`gb_LinkTarget__use_zstd`).
- Update auxiliary files (download.lst, distro-configs, etc.).
C++ Implementation (Part 2b):
- Implement `InflateZstd` (in `include/package`) and `InflaterBytesZstd`
(in `package/inc`) inheriting from `Inflater`/`InflaterBytes`.
- Use the zstd streaming API (`ZSTD_decompressStream`) following the
existing single-call pattern established by the zlib implementation.
- Manage context (`ZSTD_DCtx`) and input buffer (`ZSTD_inBuffer`) state.
- Handle errors, stream completion (`ret == 0`), and input truncation.
- Add new classes to `package/Library_package2.mk` build.
This completes the infrastructure for zstd decompression support.
The next step (Part 2c) involves adding logic to select the
appropriate Inflater based on the ZIP entry's compression method ID.
Change-Id: Ia673f3f19b6a751ba5225394fcf8c3f145c4ae63
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/184243
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>
b410749d30