Install GCC for sanitizer library support in CI

CI was failing to generate asan/tsan configurations because sanitizer
runtime libraries (libasan, libtsan) were not available. While clang++
is the primary compiler, the build system falls back to gcc's sanitizer
libraries via PlatformUtils.locateLibrary().

Changes:
- Install gcc/g++ in both glibc test jobs (amd64, aarch64)
- Remove g++ removal step in aarch64 job
- Add comments explaining sanitizer library dependency

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: jbachorik

.github/workflows/test_workflow.yml

@@ -66,6 +66,9 @@ jobs:
           sudo apt-get install -y curl zip unzip libgtest-dev libgmock-dev binutils
           # Install debug symbols for system libraries
           sudo apt-get install -y libc6-dbg
+          # Install GCC with sanitizer support (provides libasan, libtsan for asan/tsan builds)
+          # Even though clang is the primary compiler, the build falls back to gcc's sanitizer libs
+          sudo apt-get install -y gcc g++
           if [[ ${{ matrix.java_version }} =~ "-zing" ]]; then
             sudo apt-get install -y g++-9 gcc-9
             sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 100 --slave /usr/bin/g++ g++ /usr/bin/g++-9
@@ -297,11 +300,12 @@ jobs:
         if: steps.set_enabled.outputs.enabled == 'true'
         run: |
           sudo apt update -y
-          sudo apt remove -y g++
-          sudo apt autoremove -y
+          # Don't remove g++ - keep gcc for sanitizer libraries (libasan, libtsan)
           sudo apt install -y curl zip unzip clang make build-essential binutils
           # Install debug symbols for system libraries
           sudo apt install -y libc6-dbg
+          # Ensure gcc/g++ are installed for sanitizer support
+          sudo apt install -y gcc g++
           if [[ ${{ matrix.java_version }} =~ "-zing" ]]; then
             sudo apt -y install g++-9 gcc-9
             sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 100 --slave /usr/bin/g++ g++ /usr/bin/g++-9