[BUG] bytes lost (byteRcvLoss) reporting in stats is broken in 1.5.0

[maxtomilov]

Since 1.5.0 SRT_TRACEBSTATS::byteRcvLoss retrieved with srt_bstats always contain the same value as byteRecv (as all packets were lost). Looks like it was broken in 5f7bc23 and should be set to m_stats.rcvr.lost.trace.bytesWithHdr() instead of m_stats.rcvr.recvd.trace.bytesWithHdr in srt::CUDT::bstats.

[maxtomilov]

diff --git a/srtcore/core.cpp b/srtcore/core.cpp
index 6fd28c9..b07dc96 100644
--- a/srtcore/core.cpp
+++ b/srtcore/core.cpp
@@ -7401,7 +7401,7 @@ void srt::CUDT::bstats(CBytePerfMon *perf, bool clear, bool instantaneous)
         perf->byteRecv       = m_stats.rcvr.recvd.trace.bytesWithHdr();
         perf->byteRecvUnique = m_stats.rcvr.recvdUnique.trace.bytesWithHdr();
         perf->byteRetrans    = m_stats.sndr.sentRetrans.trace.bytesWithHdr();
-        perf->byteRcvLoss    = m_stats.rcvr.recvd.trace.bytesWithHdr();
+        perf->byteRcvLoss    = m_stats.rcvr.lost.trace.bytesWithHdr();
 
         perf->pktSndDrop  = m_stats.sndr.dropped.trace.count();
         perf->pktRcvDrop  = m_stats.rcvr.dropped.trace.count() + m_stats.rcvr.undecrypted.trace.count();