Add a GitHub Action for Ubuntu builds

The actions tests both g++ 5.5 and clang++ 6, with ubsan, asan and
Valgrind memcheck.

[ci skip]

.github/workflows/build-ubuntu.yml

@@ -0,0 +1,101 @@
+# Copyright (c) 2021 Morwenn
+# SPDX-License-Identifier: MIT
+
+name: Ubuntu Builds
+
+on:
+  push:
+    paths:
+      - 'CMakeLists.txt'
+      - 'cmake/**'
+      - 'examples/**'
+      - 'include/**'
+      - 'testsuite/**'
+  pull_request:
+    paths:
+      - 'CMakeLists.txt'
+      - 'cmake/**'
+      - 'examples/**'
+      - 'include/**'
+      - 'testsuite/**'
+
+jobs:
+  build:
+    runs-on: ubuntu-16.04
+
+    strategy:
+      fail-fast: false
+      matrix:
+        # Default configuration corresponds to a release
+        # build without additional tooling, also provides
+        # default options for other builds
+        cxx:
+          - g++-5
+          - clang++-6.0
+        build_type: [Release]
+        sanitize: ['']
+        valgrind: [OFF]
+
+        # Below are debug builds with tooling
+        include:
+          # GCC builds
+          - cxx: g++-5
+            build_type: Debug
+            valgrind: ON
+          - cxx: g++-5
+            build_type: Debug
+            sanitize: address
+          - cxx: g++-5
+            build_type: Debug
+            sanitize: undefined
+          # Clang builds
+          - cxx: clang++-6.0
+            build_type: Debug
+            valgrind: ON
+          - cxx: clang++-6.0
+            build_type: Debug
+            sanitize: address
+          - cxx: clang++-6.0
+            build_type: Debug
+            sanitize: undefined
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install Valgrind
+        if: ${{matrix.valgrind == 'ON'}}
+        run: sudo apt install -y valgrind
+
+      - name: Configure CMake
+        working-directory: ${{runner.workspace}}
+        env:
+          CXX: ${{matrix.cxx}}
+        run: |
+          cmake -H${{github.event.repository.name}} -Bbuild \
+                -DCMAKE_CONFIGURATION_TYPES=${{matrix.build_type}} \
+                -DCMAKE_BUILD_TYPE=${{matrix.build_type}} \
+                -DSANITIZE=${{matrix.sanitize}} \
+                -DUSE_VALGRIND=${{matrix.valgrind}} \
+                -G"Unix Makefiles" \
+                -DBUILD_EXAMPLES=ON
+
+      - name: Build the test suite
+        shell: bash
+        working-directory: ${{runner.workspace}}/build
+        run: cmake --build . --config ${{matrix.build_type}} -j 2
+
+      - name: Run the test suite with Memcheck
+        if: ${{matrix.valgrind != 'ON'}}
+        env:
+          CTEST_OUTPUT_ON_FAILURE: 1
+        working-directory: ${{runner.workspace}}/build
+        run: ctest -C ${{matrix.build_type}}
+
+      - name: Run the test suite
+        if: ${{matrix.valgrind == 'ON'}}
+        env:
+          CTEST_OUTPUT_ON_FAILURE: 1
+        working-directory: ${{runner.workspace}}/build
+        run: |
+          ctest -T memcheck -C ${{matrix.build_type}} -j 2
+          find ./Testing/Temporary -name "MemoryChecker.*.log" -size +1300c | xargs cat;