socketpair: optimize lock/write with RTCP packets

This patch prevents SocketPair::getRtcpInfo() to lock a mutex
during a consequent memory copy and reduce copy cpu load by using
move iterators.

Change-Id: Ie729cb0677c45639f5a92ae842e93032c26f1a02

src/media/socket_pair.cpp

@@ -261,11 +261,14 @@ SocketPair::saveRtcpPacket(uint8_t* buf, size_t len)
 std::vector<rtcpRRHeader>
 SocketPair::getRtcpInfo()
 {
-    std::lock_guard<std::mutex> lock(rtcpInfo_mutex_);
-    std::vector<rtcpRRHeader> vect(listRtcpHeader_.size());
-    std::copy_n(listRtcpHeader_.begin(), listRtcpHeader_.size(), vect.begin());
-    listRtcpHeader_.clear();
-    return vect;
+    decltype(listRtcpHeader_) l;
+    {
+        std::lock_guard<std::mutex> lock(rtcpInfo_mutex_);
+        if (listRtcpHeader_.empty())
+            return {};
+        l = std::move(listRtcpHeader_);
+    }
+    return {std::make_move_iterator(l.begin()), std::make_move_iterator(l.end())};
 }
 
 void