EPA: Remove SrcSpanAnn

Now that we only have a single constructor for EpAnn, And it uses a
SrcSpan for its location, we can do away with SrcSpanAnn completely.
It only existed to wrap the original SrcSpan in a location, and
provide a place for the exact print annotation.

For darwin only:
Metric Increase:
    MultiLayerModulesTH_OneShot

Updates haddock submodule