Notes for libffi - reproducible builds result

Version annotated: 3.2.1-8
Identified issues:
Identifier: build_path_captured_in_assembly_objects
Description GNU as doesn't support BUILD_PATH_PREFIX_MAP, so objects compiled from
assembly sources capture the build path.

Our notes about issues affecting packages are stored in notes.git and are targeted at packages in Debian in 'unstable/amd64' (unless they say otherwise).