[ci] introduce CI to build examples against LLVM 14 to 16

Simple CI workflow that will build both C and Rust examples.

.github/docker/Dockerfile.ubuntu

@@ -0,0 +1,44 @@
+ARG VERSION="22.04"
+FROM ubuntu:${VERSION}
+
+ARG LLVM_VERSION="14"
+ENV LLVM_VERSION=$LLVM_VERSION
+
+ARG SHORTNAME="jammy"
+
+RUN apt-get update && apt-get install -y curl gnupg
+RUN if [ "${LLVM_VERSION}" = "16" ]; \
+    then \
+        echo "\n\
+deb http://apt.llvm.org/${SHORTNAME}/ llvm-toolchain-${SHORTNAME} main\n\
+deb-src http://apt.llvm.org/${SHORTNAME}/ llvm-toolchain-${SHORTNAME} main\n\
+"  >> /etc/apt/sources.list;\
+    else \
+        echo "\n\
+deb http://apt.llvm.org/${SHORTNAME}/ llvm-toolchain-${SHORTNAME}-${LLVM_VERSION} main\n\
+deb-src http://apt.llvm.org/${SHORTNAME}/ llvm-toolchain-${SHORTNAME}-${LLVM_VERSION} main\n\
+"  >> /etc/apt/sources.list; \
+    fi
+RUN curl -L https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -
+
+ARG DEBIAN_FRONTEND="noninteractive"
+ENV TZ="Etc/UTC"
+
+RUN apt-get update && apt-get install -y \
+      libelf-dev \
+      zlib1g-dev \
+      libbfd-dev \
+      clang-${LLVM_VERSION} \
+      libclang-${LLVM_VERSION}-dev \
+      libclang-common-${LLVM_VERSION}-dev \
+      libclang1-${LLVM_VERSION} \
+      llvm-${LLVM_VERSION} \
+      llvm-${LLVM_VERSION}-dev \
+      llvm-${LLVM_VERSION}-runtime \
+      libllvm${LLVM_VERSION} \
+      make pkg-config \
+      rustc cargo rustfmt \
+      sudo \
+      && apt-get -y clean
+
+RUN ln -s /usr/bin/clang-${LLVM_VERSION} /usr/bin/clang && ln -s /usr/bin/llvm-strip-${LLVM_VERSION} /usr/bin/llvm-strip

.github/workflows/build.yml

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+name: libbpf-bootstrap build
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build_libbpf_bootstrap:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        llvm: [14, 15, 16]
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        submodules: recursive
+    - name: Build container
+      uses: docker/build-push-action@v3
+      with:
+        push: false
+        build-args: LLVM_VERSION=${{ matrix.llvm }}
+        file: ./.github/docker/Dockerfile.ubuntu
+        tags: build_container
+    - name: Build examples/c
+      run: |
+        docker run \
+          -v $(pwd):/libbpf-bootstrap \
+          build_container \
+          /bin/bash -c \
+          'cd /libbpf-bootstrap/examples/c && make'
+    - name: Build examples/rust
+      run: |
+        docker run \
+          -v $(pwd):/libbpf-bootstrap \
+          build_container \
+          /bin/bash -c \
+          'cd /libbpf-bootstrap/examples/rust && cargo build'