[eclipse-wakaamaGH-494] ci: Build and test on multiple architectures

This also fixes the CMake build on big endian architectures.

This is more complex than it should be because...
- Ubuntu 20.04 does not support many architectures, Debian does (e.g.
  ARMv5, MIPSel)
- CMake versions before 3.19 are affected by
  https://gitlab.kitware.com/cmake/cmake/-/issues/20568

Signed-off-by: Reto Schneider <[email protected]>

.github/workflows/multiarch.yaml

@@ -0,0 +1,46 @@
+name: Foreign architectures
+
+on: [push, pull_request]
+
+jobs:
+  multiarch:
+    runs-on: ubuntu-20.04
+    env:
+       cmake_version: 3.20.0
+    strategy:
+      fail-fast: false
+      matrix:
+        arch: ["armv6", "armv7", "aarch64", "s390x", "ppc64le"]
+    steps:
+    - name: Checkout code including full history and submodules
+      uses: actions/checkout@v2
+      with:
+        submodules: true
+        fetch-depth: 0
+    - name: Build and test
+      uses: uraimo/[email protected]
+      id: runcmd
+      with:
+        arch: ${{ matrix.arch }}
+        distro: buster
+        githubToken: ${{ github.token }}
+        install: |
+          apt update
+          apt -qy --no-install-recommends install libcunit1-dev ninja-build unzip wget build-essential
+          # Workaround because of https://gitlab.kitware.com/cmake/cmake/-/issues/20568
+          # Please remove once CMake 3.19 or newer is available in the repository
+          apt -qy --no-install-recommends install dirmngr gpg gpg-agent
+          echo deb-src http://archive.raspbian.org/raspbian buster main contrib non-free >> /etc/apt/sources.list
+          apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9165938D90FDDD2E
+          apt update
+          apt -qy --no-install-recommends build-dep cmake
+          wget https://github.com/Kitware/CMake/releases/download/v${{ env.cmake_version }}/cmake-${{ env.cmake_version }}.tar.gz
+          tar xf cmake-${{ env.cmake_version }}.tar.gz
+          cd cmake-${{ env.cmake_version }}
+          ./bootstrap -- -DCMAKE_USE_OPENSSL=OFF -DBUILD_TESTING=OFF
+          make -j $(nproc)
+          make install
+          cd ..
+          rm -r cmake-${{ env.cmake_version }} cmake-${{ env.cmake_version }}.tar.gz
+        run: |
+          tools/ci/run_ci.sh --build --run-tests

core/wakaama.cmake

@@ -37,8 +37,11 @@ if(NOT DEFINED LWM2M_LITTLE_ENDIAN)
          set(LWM2M_LITTLE_ENDIAN TRUE)
     endif()
 endif()
+
 if (LWM2M_LITTLE_ENDIAN)
     set(WAKAAMA_DEFINITIONS ${WAKAAMA_DEFINITIONS} -DLWM2M_LITTLE_ENDIAN)
+else()
+    set(WAKAAMA_DEFINITIONS ${WAKAAMA_DEFINITIONS} -DLWM2M_BIG_ENDIAN)
 endif()
 
 # Set the LWM2M version