Prototype - Python frames

[r1viollet]

What does this PR do?

Prototype using libaustin to include information on python frames. This uses vm_reads so requires ptrace capabilities.

The method to lookup frames is really experimental:

• We basically look for a register that makes sense

Limitations

The build parts are not sorted out yet

• This does not build on musl (due to libaustin not building on alpine afaik)
• The .a from libaustin is not propagated correctly. I manually built it and copied it on ubuntu 20 for agent investigations from the libaustin branch.

The synchronisation is not perfect. By the time we get the event, python may have done a lot of things (frames can get reused). This gives us messy frames (they do not aggregate well).

This takes some amount of CPU. We need to perform a lookup quite often.

Licensing

This is probably the most complex topici.

[sanchda]

Oh wow, just saw this--really cool 8)