GHC build with -haddock option fails on GHC 8.10

Summary

Build failed with error:

compiler/GHC/Core/Opt/WorkWrap/Utils.hs:140:3: error:
    parse error on input ‘{’
    |
140 |   { wo_fam_envs          :: !FamInstEnvs
    |   ^
Command failed

@int-e and @geekosaur in GHC chat pointed out that it looks like another instance of this bug:

2c25fff6

Steps to reproduce

./boot
./configure
hadrian/build -j --flavour=Quick

Expected behavior

GHC builds successfully

Environment

• GHC version used: 8.10
• Operating System: ArchLinux