Add CXX child crate

This adds CXX FFI for the dcSCTP rust library to integrate it into a C++
application.

Author: boivie

.github/workflows/ci.yml

@@ -72,3 +72,15 @@ jobs:
         env:
           RUSTDOCFLAGS: "--deny warnings"
         run: cargo doc --no-deps --all-features --document-private-items
+
+  build-cxx:
+    name: cxx (build)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+      - name: Build and sanity test
+        run: |
+          cd dcsctp-cxx/
+          make clean all run

.gitignore

@@ -1,5 +1,7 @@
+/dcsctp-cxx/examples/main
 /fuzz/artifacts/
 /fuzz/corpus/
 /fuzz/coverage/
 /fuzz/target/
 /target/
+*.o