Fix a memleak in CLPF.

The memleak appeared in eb5794da.

Change-Id: Ifdd6d64aafa0d0ce4dfaf1844f594d5f843bf2e0

av1/common/clpf.c

@@ -168,6 +168,7 @@ int av1_clpf_frame(const YV12_BUFFER_CONFIG *orig_dst,
 
     aom_free(cache);
     aom_free(cache_ptr);
+    aom_free(cache_dst);
   }
 
   return block_index;