clean up valgrind error

[slingamn]

This ensures that the new[] call here:

libtorrent/src/utils/partial_queue.h

Line 82 in aa363d8

m_data.reset(new mapped_type[ls * num_layers]);

is paired with a delete[] call instead of a delete call, fixing this class of Valgrind errors:

==1324887== Mismatched new/delete size value: 4
==1324887==    at 0x484A5B9: operator delete(void*, unsigned long) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==1324887==    by 0x49C0307: operator() (unique_ptr.h:99)
==1324887==    by 0x49C0307: ~unique_ptr (unique_ptr.h:404)
==1324887==    by 0x49C0307: ~PartialQueue (partial_queue.h:28)
==1324887==    by 0x49C0307: ~ChunkSelector (chunk_selector.h:24)
==1324887==    by 0x49C0307: torrent::DownloadMain::~DownloadMain() (download_main.cc:88)
==1324887==    by 0x49C4210: operator() (unique_ptr.h:99)
==1324887==    by 0x49C4210: operator() (unique_ptr.h:93)
==1324887==    by 0x49C4210: ~unique_ptr (unique_ptr.h:404)
==1324887==    by 0x49C4210: torrent::DownloadWrapper::~DownloadWrapper() (download_wrapper.cc:63)
==1324887==    by 0x495233C: torrent::DownloadManager::erase(torrent::DownloadWrapper*) (download_manager.cc:62)
==1324887==    by 0x166950: core::DownloadList::erase(std::_List_iterator<core::Download*>) (download_list.cc:211)
==1324887==    by 0x1691B7: erase_ptr (download_list.cc:190)
==1324887==    by 0x1691B7: core::DownloadList::process_meta_download(core::Download*) (download_list.cc:709)
==1324887==    by 0x4985005: operator() (std_function.h:591)
==1324887==    by 0x4985005: torrent::utils::Scheduler::perform(std::chrono::duration<long, std::ratio<1l, 1000000l> >) (scheduler.cc:171)
==1324887==    by 0x4987C37: torrent::utils::Thread::event_loop() (thread.cc:188)
==1324887==    by 0x15B825: main (main.cc:441)
==1324887==  Address 0x6460160 is 0 bytes inside a block of size 1,024 alloc'd
==1324887==    at 0x48485C3: operator new[](unsigned long) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==1324887==    by 0x49B7533: enable (partial_queue.h:82)
==1324887==    by 0x49B7533: torrent::ChunkSelector::initialize(torrent::ChunkStatistics*) (chunk_selector.cc:28)
==1324887==    by 0x49C47A5: torrent::DownloadWrapper::receive_initial_hash() (download_wrapper.cc:140)
==1324887==    by 0x4985005: operator() (std_function.h:591)
==1324887==    by 0x4985005: torrent::utils::Scheduler::perform(std::chrono::duration<long, std::ratio<1l, 1000000l> >) (scheduler.cc:171)
==1324887==    by 0x4987C37: torrent::utils::Thread::event_loop() (thread.cc:188)
==1324887==    by 0x15B825: main (main.cc:441)

There should be no functional change. On the plus side, with this patch, I no longer see any errors in valgrind, including the DHT errors from #166.