clipper2c-sys is a low-level Rust FFI binding crate for Clipper2C, needed by
the Rust clipper2 crate and ultimately by the raygeo/rayforge dependency chain.

This packaging uses the newly available Debian Clipper2 C++ library instead of
the bundled upstream Clipper2 copy:

- debian/debcargo.toml Build-Depends and Depends on libclipper2-dev.
- debian/debcargo.toml excludes clipper2c/vendor/Clipper2/** from the repacked
  +dfsg tarball.
- debian/patches/use-system-clipper2.patch compiles only the crate's C wrapper
  sources and dynamically links against libClipper2utils and libClipper2 from
  libclipper2-dev.

Other Debian patches:

- relax-cc-version.patch relaxes the cc build-dependency from 1.2.61 to
  Debian's 1.2.60.
- remove-unavailable-criterion-benchmark.patch removes a benchmark-only
  Criterion 0.7 dependency; Debian unstable currently has Criterion 0.5.
- use-tempdir-for-svgreader-tests.patch makes SVG reader tests write fixtures
  under the system temporary directory so installed-source autopkgtests can run
  against the read-only cargo registry tree.

Feature/test handling:

- collapse_features = true is enabled.
- update-bindings and the aggregate feature test are marked test_is_broken
  because update-bindings is a maintainer regeneration mode that writes
  generated bindings under CARGO_MANIFEST_DIR, which is read-only during
  Debian autopkgtests.
- The runtime tests for bindgen, default, generate-bindings, serde, and the
  no-feature library package remain enabled.

Validation on 2026-07-16:

- ./update.sh clipper2c-sys succeeds on current Rust Team origin/master with
  only the expected unreleased generated changelog distribution marker.
- ../build.sh clipper2c-sys builds against archive libclipper2-dev 2.0.1-1
  without local .deb inputs.
- sbuild result: Status successful, Autopkgtest pass, Lintian successful
  (worst tag: warn).
- Raw autopkgtest summary: bindgen/default/generate-bindings/serde/no-feature
  tests PASS; aggregate and update-bindings are FLAKY as documented above.
- The debcargo helper reports UNKNOWN while parsing the autopkgtest log because
  it sees the documented FLAKY update-bindings failures; the raw autopkgtest
  summary says the run was successful.
- Explicit deep lintian command:
  lintian --display-info --pedantic rust-clipper2c-sys_0.2.0+dfsg-1_amd64.changes
  Remaining tags: distribution-and-changes-mismatch for the generated
  UNRELEASED changelog distribution, extended-description-is-probably-too-short,
  package-contains-documentation-outside-usr-share-doc for upstream files in
  the cargo registry source tree, package-uses-old-debhelper-compat-version 13,
  and upstream-metadata-file-is-missing.
