kas/common/base.yml: enable use of ccache for the builds

- Enable Compiler cache for the builds
- It reduces build time during recompilation by caching previous compilations,
    and detecting when same compilation is being done again
- Tested nanopi neo image build time got reduced by 5 minutes

Signed-off-by: Badrikesh Prusty <badrikesh.prusty@siemens.com>

kas/common/base.yml

@@ -36,3 +36,5 @@ local_conf_header:
   base: |
     CONF_VERSION = "1"
     ISAR_CROSS_COMPILE = "1"
+  ccache: |
+    USE_CCACHE = "1"