[core] Added missing lock for isRcvDataReady()
[core] Added missing lock for isRcvDataReady()

ethouris/srt,ethouris/srt,Haivision/srt,Cinegy/srt,Haivision/srt,ethouris/srt,Cinegy/srt,Cinegy/srt,ethouris/srt,Haivision/srt,Haivision/srt,Cinegy/srt