Add Makefile rules to clear cache.
Add Makefile rules to clear cache.

osmium-org/osmium,wffurr/osmium,copyliu/osmium,wffurr/osmium,osmium-org/osmium,osmium-org/osmium,osmium-org/osmium,wffurr/osmium,copyliu/osmium,wffurr/osmium,copyliu/osmium