CTF1.8 structure fields beginning with an underscore should have their underscore removed.

[arfio]

Bug Description:

As specified in the CTF1.8 specifications:

Fields starting with an underscore should have their leading underscore removed by the CTF trace readers.

This is an issue because a lot of analyses depend on vtid, tid and other fields which are prefixed by an underscore, and with CTF2 we would need to check for both fields. A better fix would be to remove the underscore and modify all the analyses so that they handle the fields using no underscore in the prefix.
https://diamon.org/ctf/v1.8.3/

Steps to Reproduce:

1. Generate a CTF2 trace with vtid context and cyg_profile events
2. Try to make the callstack analysis work