[cache] Miscellaneous clean-ups. * src/cache/ftccache.c (ftc_get_top_node_for_hash, FTC_Cache_Clear): Remove barely used variables. (ftc_cache_add): Adjust casting. * src/cache/ftccmap.c (FTC_CMapCache_Lookup): Remove casting. * src/cache/ftcsbits.c (ftc_snode_load): Remove casting.