tools: ccache: disable build testing

The ccache build relies on doctest, which
is useless and can be disabled.

Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
Link: https://github.com/openwrt/openwrt/pull/17700
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

tools/ccache/Makefile

@@ -22,6 +22,7 @@ CMAKE_HOST_OPTIONS += \
 	-DCMAKE_SKIP_RPATH=FALSE \
 	-DCMAKE_INSTALL_RPATH="${STAGING_DIR_HOST}/lib" \
 	-DENABLE_DOCUMENTATION=OFF \
-	-DREDIS_STORAGE_BACKEND=OFF
+	-DREDIS_STORAGE_BACKEND=OFF \
+	-DENABLE_TESTING=OFF
 
 $(eval $(call HostBuild))