[core] Replace hacky static_assert by SRT_STATIC_ASSERT
[core] Replace hacky static_assert by SRT_STATIC_ASSERT

Remove local static SRTDATA_MAXSIZE since there is another one in
global namespace.

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