Use a RelocationRef instead of a relocation_iterator.
No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180723 91177308-0d34-0410-b5e6-96231b3b80d8
Update the documentation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180725 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180729 91177308-0d34-0410-b5e6-96231b3b80d8