Build Android in cubeb's CI on the 3 main arch Gecko supports

.github/workflows/build.yml

@@ -71,9 +71,11 @@ jobs:
     runs-on: ubuntu-22.04
     env:
       BUILD_TYPE: ${{ matrix.type }}
+      BUILD_ARCH: ${{ matrix.arch }}
     strategy:
       matrix:
         type: [Release, Debug]
+        arch: [arm64-v8a, armeabi-v7a, x86_64]
     steps:
     - uses: actions/checkout@v4
       with:
@@ -81,7 +83,7 @@ jobs:
 
     - name: Configure CMake
       shell: bash
-      run: cmake -S . -B build -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake -DANDROID_NATIVE_API_LEVEL=android-28 -DANDROID_ABI=arm64-v8a
+      run: cmake -S . -B build -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake -DANDROID_NATIVE_API_LEVEL=android-28 -DANDROID_ABI=$BUILD_ARCH
 
     - name: Build
       shell: bash