Code safety: BlockCache isn't supposed to be copied/moved

src/block_cache.cpp

@@ -29,7 +29,7 @@ static constexpr char cache_name[] = "p2pool.cache";
 
 namespace p2pool {
 
-struct BlockCache::Impl
+struct BlockCache::Impl : public nocopy_nomove
 {
 #if defined(__linux__) || defined(__unix__) || defined(_POSIX_VERSION)
 

src/block_cache.h

@@ -23,7 +23,7 @@ struct PoolBlock;
 class SideChain;
 class P2PServer;
 
-class BlockCache
+class BlockCache : public nocopy_nomove
 {
 public:
 	BlockCache();