factorize oldest compiler

Author: robUx4

.github/workflows/linux.yaml

@@ -47,62 +47,20 @@ jobs:
       - name: Test installation
         run: cmake --install _build --prefix ${GITHUB_WORKSPACE}/_built
 
-  GCC-7:
+  Oldest:
     runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        cxx: ['g++-7', 'clang++-7']
     env:
       CMAKE_OPTIONS: -DDEV_MODE=ON -DBUILD_TESTING=ON
       CMAKE_MATROSKA_OPTIONS: -DBUILD_EXAMPLES=ON
-      CC: gcc-7
-      CXX: g++-7
+      CXX: ${{matrix.cxx}}
     steps:
       - name: install gcc-7
         run: |
           sudo add-apt-repository --yes --update ppa:ubuntu-toolchain-r/test
-          sudo DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends g++-7
-
-      - name: list compilers
-        run: dpkg --list | grep compiler
-
-      - name: Get pushed code
-        uses: actions/checkout@v4
-
-      - name: Checkout libebml
-        uses: actions/checkout@v4
-        with:
-          repository: Matroska-Org/libebml
-          path: libebml
-          # minimum version we support ref: 'release-1.4.3'
-
-      - name: Configure libebml
-        run: cmake -S libebml -B libebml/_build ${{ env.CMAKE_OPTIONS }}
-
-      - name: Build libebml
-        run: cmake --build libebml/_build --parallel
-
-      - name: Install libebml
-        run: cmake --install libebml/_build --prefix ${GITHUB_WORKSPACE}/_built
-
-      - name: Configure
-        run: cmake -S . -B _build  ${{ env.CMAKE_OPTIONS }} ${{ env.CMAKE_MATROSKA_OPTIONS }} -DEBML_DIR="${GITHUB_WORKSPACE}/_built/lib/cmake/EBML"
-
-      - name: Build
-        run: cmake --build _build --parallel
-
-      - name: Test installation
-        run: cmake --install _build --prefix ${GITHUB_WORKSPACE}/_built
-
-  Clang-7:
-    runs-on: ubuntu-20.04
-    env:
-      CMAKE_OPTIONS: -DDEV_MODE=ON -DBUILD_TESTING=ON
-      CMAKE_MATROSKA_OPTIONS: -DBUILD_EXAMPLES=ON
-      CC: clang-7
-      CXX: clang++-7
-    steps:
-      - name: install clang-7
-        run: |
-          sudo add-apt-repository --yes --update ppa:ubuntu-toolchain-r/test
-          sudo DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends clang++-7
+          sudo DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends ${{matrix.cxx}}
 
       - name: list compilers
         run: dpkg --list | grep compiler