linux: parse ELF and DWARF to remove libc dependency

[laytan]

[laytan]

• [x] figure out why the line program has direntry 0 (no directory) for the first / main.odin file
• [ ] clean up a lot lot
• [ ] ~~relocate dwarf sections (does this have a use for Odin?)~~ (it does not)
• [ ] make more use of iterators over allocations in the dwarf package
• [ ] make an encapsulating package, similar to the darwin CoreSymbolication API, handles caching, resolving, parsing etc. and just provides symbol info from an address
• [ ] same thing for unwinding, make it a package, probably nice to have an unwind package, with implementations for each target
• [ ] unwinding stops as soon as a libc proc is hit, backtrace keeps going and gets back to useful info, need that too
• [ ] make bufio.Reader support seeking and use it (massive perf gains)
• [ ] debug -use-separate-modules, seems to have some stuff going wrong and is a good stress test of compile units

[laytan]

So for going through libc I am thinking we have to hardware unwind instead of virtual unwind, because there are no cu/fde frames in the debug info for it. Not 100% but that is my theory.

OR, there is some kind of link in the ELF that links to the libc file, which we then need to parse separately?