maxWorkerArgs handling was accidentally lost 3 years ago
in a major update of demand analysis
    commit 0831a12e



Old regression is noticeable as:
- code bloat (requires stack reshuffling)
- compilation slowdown (more code to optimise/generate)
- and increased heap usage (DynFlags unboxing/reboxing?)

On a simple compile benchmark this change causes heap
allocation drop from 70G don to 67G (ghc perf build).

Signed-off-by: Sergei Trofimovich <siarheit@google.com>

Reviewers: simonpj, ezyang, goldfire, austin, bgamari

Reviewed By: simonpj, ezyang

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2503

GHC Trac Issues: #11565