[core] Added steady_clock typedef to CUDT Minor refactoring
[core] Added steady_clock typedef to CUDT
Minor refactoring

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