Missing span when re-exporting module

ExportModule declarations should have one entry in srcInfoPoints (the location of the "module" keyword), but currently the list is empty. This should be an easy fix.

Example

module Test (module Prelude) where

has

SpanInfo (Span (Pos 1 14) (Pos 1 27)) []

as SpanInfo for the module-export, whereas it should be

SpanInfo (Span (Pos 1 14) (Pos 1 27)) [Span (Pos 1 14) (Pos 1 19)]