[BUG] Order of set options.

[mycrl]

Describe the bug
The order in which the options are set affects whether the other options are set successfully.

To Reproduce

int latency = 20;
srt_setsockflag(sock, SRTO_RCVLATENCY, &latency, sizeof(int));
srt_setsockflag(sock, SRTO_TRANSTYPE, &SRTT_LIVE, sizeof(SRTT_LIVE));

RCVLATENCY still defaults to 120ms.

Expected behavior

Hopefully the RCVLATENCY value has been set to 20ms.

Desktop (please provide the following information):

• OS: Windows, Linux, Macos
• SRT Version / commit ID: 1.5.3

Additional context

int latency = 20;
srt_setsockflag(sock, SRTO_TRANSTYPE, &SRTT_LIVE, sizeof(SRTT_LIVE));
srt_setsockflag(sock, SRTO_RCVLATENCY, &latency, sizeof(int));

If you first Set real-time mode and then set latency, it will be set successfully.

I don't think the settings of the setup's options should be related to the order, it's not intuitive and it's not developer friendly.

[ethouris]

@maxsharabayko I think we need a list of options that are set to their defaults for particular mode in the description. Currently this is only mentioned at the options that are being set, and also not all - SRTO_LATENCY isn't among them.

[maxsharabayko]

There is also a dependency between SRTO_RCVBUF and SRTO_FC (#700).