Compile warning: libbitcoin_server_a-processblock.o

[AltJ]

On Ubuntu 18.04

  CXX      libbitcoin_server_a-processblock.o
In file included from ./serialize.h:39:0,
                 from ./chain/outpoint.h:24,
                 from ./chain/txin.h:24,
                 from ./chain/tx.h:25,
                 from ./chain/block.h:24,
                 from ./chain/blockindex.h:25,
                 from blockstorage/blockstorage.h:5,
                 from processblock.cpp:31:
./prevector.h: In member function 'void CCheckQueue<T>::Add(std::vector<T>&) [with T = CScriptCheck]':
./prevector.h:280:98: warning: '<anonymous>.prevector<28, unsigned char>::_union.prevector<28, unsigned char>::direct_or_indirect::<anonymous>.prevector<28, unsigned char>::direct_or_indirect::<unnamed struct>::indirect' may be used uninitialized in this function [-Wmaybe-uninitialized]
     const T *indirect_ptr(difference_type pos) const { return reinterpret_cast<const T *>(_union.indirect) + pos; }
                                                                                           ~~~~~~~^~~~~~~~

[Greg-Griffith]

fixed in #265