CI: add monthly gcc cross compile jobs

Build only gcc cross compile jobs are added with monthly run to catch
rare errors, mostly 32bit <--> 64bit
diff --git a/.github/workflows/cross-zoo.yml b/.github/workflows/cross-zoo.yml
new file mode 100644
index 0000000..e2a5816
--- /dev/null
+++ b/.github/workflows/cross-zoo.yml
@@ -0,0 +1,110 @@
+#
+# this is naamed "zoo" after OpenSSL "cross zoo pipeline"
+#
+name: Cross Compile
+
+on:
+  schedule:
+    - cron: "0 0 21 * *"
+
+permissions:
+  contents: read
+
+jobs:
+  cross-compilation:
+    strategy:
+      matrix:
+        platform: [
+          {
+            arch: aarch64-linux-gnu,
+            libs: libc6-dev-arm64-cross,
+            target: linux-aarch64
+          }, {
+            arch: alpha-linux-gnu,
+            libs: libc6.1-dev-alpha-cross,
+            target: linux-alpha-gcc
+          }, {
+            arch: arm-linux-gnueabi,
+            libs: libc6-dev-armel-cross,
+            target: linux-armv4
+          }, {
+            arch: arm-linux-gnueabihf,
+            libs: libc6-dev-armhf-cross,
+            target: linux-armv4
+          }, {
+            arch: hppa-linux-gnu,
+            libs: libc6-dev-hppa-cross,
+            target: -static linux-generic32
+          }, {
+            arch: m68k-linux-gnu,
+            libs: libc6-dev-m68k-cross,
+            target: -static -m68040 linux-latomic
+          }, {
+            arch: mips-linux-gnu,
+            libs: libc6-dev-mips-cross,
+            target: -static linux-mips32
+          }, {
+            arch: mips64-linux-gnuabi64,
+            libs: libc6-dev-mips64-cross,
+            target: -static linux64-mips64
+          }, {
+            arch: mipsel-linux-gnu,
+            libs: libc6-dev-mipsel-cross,
+            target: linux-mips32
+          }, {
+            arch: powerpc64le-linux-gnu,
+            libs: libc6-dev-ppc64el-cross,
+            target: linux-ppc64le
+          }, {
+            arch: riscv64-linux-gnu,
+            libs: libc6-dev-riscv64-cross,
+            target: linux64-riscv64
+          }, {
+            arch: s390x-linux-gnu,
+            libs: libc6-dev-s390x-cross,
+            target: linux64-s390x
+          }, {
+            arch: sh4-linux-gnu,
+            libs: libc6-dev-sh4-cross,
+            target: no-async linux-latomic
+          }, {
+            arch: hppa-linux-gnu,
+            libs: libc6-dev-hppa-cross,
+            target: linux-generic32,
+          }, {
+            arch: m68k-linux-gnu,
+            libs: libc6-dev-m68k-cross,
+            target: -mcfv4e linux-latomic
+          }, {
+            arch: mips-linux-gnu,
+            libs: libc6-dev-mips-cross,
+            target: linux-mips32
+          }, {
+            arch: mips64-linux-gnuabi64,
+            libs: libc6-dev-mips64-cross,
+            target: linux64-mips64
+          }, {
+            arch: sparc64-linux-gnu,
+            libs: libc6-dev-sparc64-cross,
+            target: linux64-sparcv9
+          }
+        ]
+    runs-on: ubuntu-latest
+    steps:
+    - name: install packages
+      run: |
+        sudo apt-get update
+        sudo apt-get -yq --force-yes install \
+            gcc-${{ matrix.platform.arch }} \
+            ${{ matrix.platform.libs }}
+    - uses: actions/checkout@v2
+
+
+    - name: install quictls
+      run: |
+        QUICTLS_EXTRA_ARGS="--cross-compile-prefix=${{ matrix.platform.arch }}- ${{ matrix.platform.target }}" QUICTLS=yes scripts/build-ssl.sh
+
+    - name: Build
+      run: |
+        make ERR=1 CC=${{ matrix.platform.arch }}-gcc TARGET=linux-glibc USE_LIBCRYPT= USE_OPENSSL=1 USE_QUIC=1 USE_PROMEX=1 SSL_LIB=${HOME}/opt/lib SSL_INC=${HOME}/opt/include ADDLIB="-Wl,-rpath,${HOME}/opt/lib"
+