Code cleanup: Moved AttributeExpander specific helpers out of Util.

* As I was looking at some include* specific code changes, I found
  AttributeExpander specific helpers in Util -- there is no reason
  for them to be there since they are extremely specific to attr.
  expansion and have no value to other classes.

* Added a few FIXMEs to dead/duplicate utility functions.  Worth
  cleaning up at some point.

Change-Id: I23ab23a81d93c87efe51bd5c38b028d0ce015af2
Merge "Code cleanup: Moved AttributeExpander specific helpers out of Util."