Alllow static pointers to local closed definitions

A limitation of the original patch implementing -XStaticPointers is that while the following all work,

t1 = static not
t2 = static (\x -> case x of True -> False; False -> True)

the below does not:

t3 = static foo where foo True = False

Yet foo is perfectly "static": it's a closed expression that can readily be floated to top-level.

So in short: -XStaticPointers should not consider only expressions with top-level identifiers, but in general any closed expression (which may involve local closed identifiers too).

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	edsko, facundo.dominguez
Operating system
Architecture