[BUG] Group socket without members always return default value of options

[IvanPysmenni]

"Get" of socket option(for example SRTO_ENFORCEDENCRYPTION) from a group socket without members always return default value even if this option was set before
After set socket option to group socket without members(for example SRTO_ENFORCEDENCRYPTION=false).

Steps to reproduce the behavior:

1. Call srt_create_group for create group socket
2. Set SRTO_ENFORCEDENCRYPTION to "false"
3. Get SRTO_ENFORCEDENCRYPTION from socket and check result

Expected behavior:
After set SRTO_ENFORCEDENCRYPTION to "false' I expect to get same value from socket but instead I got "true". Same problem applied and for other options. SRTO_ENFORCEDENCRYPTION is just an example.

OS: Ubuntu 20.04 focal (x86-64)
SRT version: 1.5.3