lcov in llvm vs ptrace

[xd009642]

Because the llvm coverage instruments the binary we generally skip all the DWARF parsing etc and rely on llvm/rust knowing what they're doing and being more correct (DWARF is a mess). But this means for things like the lcov coverage reports the filenames get lost.

Instead it may be better to lean on the source analysis module and get nice demangled names of symbols etc in a file - maybe even going as far as getting the fully qualified name for the item (though this isn't super necessary as lcov uses the file name + symbol name so a human can disambiguate).