This commit reduces the size of `InstructionAddressMap` from 24 bytes to 8 bytes by dropping the `code_len` field and reducing `code_offset` to `u32` instead of `usize`. The intention is to primarily make the in-memory version take up less space, and the hunch is that the `code_len` is largely not necessary since most entries in this map are always adjacent to one another. The `code_len` field is now implied by the `code_offset` field of the next entry in the map. This isn't as big of an improvement to serialized module size as #2321 or #2322, primarily because of the switch to variable-length encoding. Despite this though it shaves about 10MB off the encoded size of the module from #2318
This is the wasmtime-debug crate, which provides functionality to
read, transform, and write DWARF section.