lintIdUnfolding could be simpler

I think that lintIdUnfolding could use maybeUnfoldingTemplate rather than the complicated linting of DFunUnfolding. Seeing as maybeUnfoldingTemplate is the thing which is used when inlining, it makes sense to use that rather than some ad-hoc reconstruction.

See https://phabricator.haskell.org/D4919 for the patch

Trac metadata

Trac field	Value
Version	8.4.3
Type	Task
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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changed milestone to %8.6.1

changed weight to 5

added Ttask Trac import labels

changed milestone to %8.8.1

These won't be fixed for in GHC 8.6.

closed

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added Pnormal label