CI: Add and use ccache in build-each-commit job

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Anthony PERARD <anthony.perard@vates.tech>

automation/build/debian/12-x86_64.dockerfile

@@ -54,6 +54,9 @@ RUN <<EOF
         expect
         qemu-system-x86
 
+        # for build-each-commit-gcc
+        ccache
+
         # for qemu-alpine-x86_64-gcc
         busybox-static
         cpio

automation/gitlab-ci/build-each-commit.sh

@@ -12,6 +12,11 @@ if [[ $? -ne 0 ]]; then
     exit 0
 fi
 
+if [ -d /usr/lib/ccache ]; then
+    echo "Building with ccache"
+    PATH="/usr/lib/ccache:$PATH"
+fi
+
 echo "Building ${BASE}..${TIP}"
 
 NON_SYMBOLIC_REF=1 ./automation/scripts/build-test.sh ${BASE} ${TIP} \