Summary:
Pull Request resolved: https://github.com/facebookexperimental/object-introspection/pull/507
OI is currently completely incompatible with anything except `x86_64`. Changing that generally is a big effort, but `oilgen` should work on other architectures. Begin adding some support for `aarch64` architecture.
This change sets up a file structure for architecture support. It pulls the 2 functions needed to make `Descs.{h,cpp}` architecture agnostic into architecture specific files for `x86_64` and `aarch64`. This enables `oilgen` (the binary) to build. At this stage `oilgen` is unable to generate working code for `aarch64`, but at least this is a step in the right direction.
Differential Revision: D61661524
