Use gcc-9 in CI

azure-pipelines.yml

       - script: |
           set -eu
           sudo apt update -y
-          sudo apt install -y python3-minimal g++-8 ccache
+          sudo apt install -y python3-minimal g++-9 ccache
           python3 -m pip install pytest pytest-xdist
         displayName: Prepare System
-      - script: python3 -u tools/ci.py -B download --cxx g++-8 -T tools/gcc-8.dds
+      - script: python3 -u tools/ci.py -B download --cxx g++-9 -T tools/gcc-9.dds
         displayName: Full CI
       - publish: _build/dds
         artifact: DDS Executable - Linux
     pool:
       vmImage: macOS-10.14
     steps:
-      - script: brew install gcc@8 ccache
+      - script: brew install gcc@9 ccache
         displayName: Prepare System
       - script: |
           set -eu
           python3 -m pip install pytest pytest-xdist
-          python3 -u tools/ci.py -B download --cxx g++-8 -T tools/gcc-8.dds
+          python3 -u tools/ci.py -B download --cxx g++-9 -T tools/gcc-9.dds
         displayName: Build and Run Unit Tests
       - publish: _build/dds
         artifact: DDS Executable - macOS

tests/dds.py

     @property
     def default_builtin_toolchain(self) -> str:
         if os.name == 'posix':
-            return ':gcc-8'
+            return ':gcc-9'
         elif os.name == 'nt':
             return ':msvc'
         else:

tools/gcc-9.dds

 C-Compiler: gcc-9
 C++-Compiler: g++-9
 Flags: -D SPDLOG_COMPILED_LIB -fconcepts -Werror=return-type
-# Optimize: True
 Debug:  True
-# Link-Flags: -fsanitize=address
-Link-Flags: -fuse-ld=lld
 Compiler-Launcher: ccache