Broken symlink in repo

[thomasjm]

A broken symlink was introduced in this commit:

d64dd4ffffae534068505b83986c8d95f8cbc3bb

at

attoparsec-aeson/src/Data/Aeson/Internal/Word8.hs

This made it impossible for me to add aeson as a Git dependency to my stack.yaml, because it fails to unpack the source tarball with an error about "Symbolic link dest not found." I think this affects versions 2.2.2.0 and 2.2.3.0.

CC @phadej