Build tests for all CMake platforms on CI

.github/workflows/riscos.yml

@@ -44,6 +44,8 @@ jobs:
           -DCMAKE_TOOLCHAIN_FILE=/home/riscos/env/toolchain-riscos.cmake \
           -DRISCOS=ON \
           -DSDL_GCC_ATOMICS=OFF \
+          -DSDL_TESTS=ON \
+          -DSDL_INSTALL_TESTS=ON \
           -DCMAKE_BUILD_TYPE=Release \
           -DCMAKE_INSTALL_PREFIX=${{ github.workspace }}/prefix_cmake
     - name: Build (CMake)