Enable in-tree builds of parallel-libs.
Enable in-tree builds of parallel-libs.

Summary:
parallel-libs needs its own changes to make this work; these are just
the LLVM changes.

Reviewers: jhen

Subscribers: llvm-commits, beanz, jprice

Differential Revision: https://reviews.llvm.org/D24402

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@281097 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm