CI: add linux-32 build

.github/workflows/build.yml

@@ -40,6 +40,10 @@ jobs:
             preset: linux
             cc: clang
             cxx: clang++
+          - runner: ubuntu-latest
+            preset: linux-32
+            cc: gcc
+            cxx: g++
 
     runs-on: ${{ matrix.os.runner }}
 
@@ -59,6 +63,14 @@ jobs:
           sudo apt install -y --no-install-recommends \
             ninja-build cmake g++ libsdl1.2-dev libsdl-image1.2-dev libncurses-dev zlib1g-dev
 
+      - name: Install Linux dependencies for 32 bit build
+        if: ${{ matrix.os.preset == 'linux-32' }}
+        run: |
+          sudo dpkg --add-architecture i386
+          sudo apt update
+          sudo apt install -y --no-install-recommends \
+            ninja-build cmake g++ g++-multilib libsdl1.2-dev:i386 libsdl-image1.2-dev:i386 libncurses-dev:i386 zlib1g-dev:i386
+
       - name: Configure CMake
         env:
           CC: ${{ matrix.os.cc }}