[LTO] Remove unused Path parameter to AddBufferFn

Summary:
With D43396, no clients use the Path parameter anymore.

Depends on D43396.

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, llvm-commits

Differential Revision: https://reviews.llvm.org/D43400

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325619 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed