ci/github: Use shallow checkouts of the yocto layers.

In the CI we don't need git repositories with the full history. So we
use shallow checkouts, this saves us time and disk space.

.github/workflows/build-elos-minimal.yml

@@ -36,8 +36,8 @@ jobs:
         run: |
           sudo locale-gen en_US.UTF-8
           mkdir -p $YOCTO_BUILD_PATH
-          git clone -b kirkstone git://git.yoctoproject.org/poky.git $YOCTO_BUILD_PATH/poky
-          git clone -b kirkstone https://github.com/openembedded/meta-openembedded.git $YOCTO_BUILD_PATH/meta-openembedded
+          git clone --depth 1 -b kirkstone git://git.yoctoproject.org/poky.git $YOCTO_BUILD_PATH/poky
+          git clone --depth 1 -b kirkstone https://github.com/openembedded/meta-openembedded.git $YOCTO_BUILD_PATH/meta-openembedded
           ln -s $(pwd) $YOCTO_BUILD_PATH/meta-elos
           
           cd $YOCTO_BUILD_PATH

ci/Dockerfile

@@ -47,8 +47,8 @@ ENV LC_ALL=en_US.UTF-8
 ENV DOCKERBUILD=1
 ENV BBCACHE="/home/ci/bbcache"
 
-RUN git clone -b kirkstone git://git.yoctoproject.org/poky.git /home/$USER/layers/poky/
-RUN git clone -b kirkstone git://git.openembedded.org/meta-openembedded /home/$USER/layers/meta-openembedded/
+RUN git clone --depth 1 -b kirkstone git://git.yoctoproject.org/poky.git /home/$USER/layers/poky/
+RUN git clone --depth 1 -b kirkstone git://git.openembedded.org/meta-openembedded /home/$USER/layers/meta-openembedded/
 
 RUN echo ". /home/$USER/layers/poky/oe-init-build-env /base/build >/dev/null" >> /home/$USER/.bashrc