merged lsd fix from RC_0_16

ChangeLog

@@ -54,6 +54,7 @@
 	* fix uTP edge case where udp socket buffer fills up
 	* fix nagle implementation in uTP
 
+	* fix local service discovery for magnet links
 	* fix bitfield issue in file_storage
 	* added work-around for MingW issue in file I/O
 	* fixed sparse file detection on windows

src/torrent.cpp

@@ -2085,8 +2085,9 @@ namespace libtorrent
 		if (m_abort) return;
 
 		// if the files haven't been checked yet, we're
-		// not ready for peers
-		if (!m_files_checked) return;
+		// not ready for peers. Except, if we don't have metadata,
+		// we need peers to download from
+		if (!m_files_checked && valid_metadata()) return;
 
 		if (!m_announce_to_lsd) return;