[LoopInfo] Port loop exit interfaces from Loop to LoopBase

This patch ports hasDedicatedExits, getUniqueExitBlocks and
getUniqueExitBlock in Loop to LoopBase so that they can be used
from other LoopBase sub-classes.

Reviewers: chandlerc, sanjoy, hfinkel, fhahn

Reviewed By: chandlerc

Differential Revision: https://reviews.llvm.org/D48817



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336572 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed