CI: tools: compile tools with ccache support for tools container

Enable ccache support for tools container, useful to speedup other
workflow even more.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
(cherry picked from commit 2781e3839e)

.github/workflows/tools.yml

@@ -110,7 +110,7 @@ jobs:
         run: |
           chown -R buildbot:buildbot openwrt
 
-      - name: Set AUTOREMOVE config for tools container
+      - name: Set configs for tools container
         if: github.event_name == 'push'
         shell: su buildbot -c "sh -e {0}"
         working-directory: openwrt
@@ -118,6 +118,7 @@ jobs:
           touch .config
           echo CONFIG_DEVEL=y >> .config
           echo CONFIG_AUTOREMOVE=y >> .config
+          echo CONFIG_CCACHE=y >> .config
 
       - name: Make prereq
         shell: su buildbot -c "sh -e {0}"