[FuzzerUtil] Partially revert D38481 on FuzzerUtil
[FuzzerUtil] Partially revert D38481 on FuzzerUtil

This is because lib/Fuzzer doesn't really depend on llvm infrastucture.
It's not easy to access the llvm hardware_concurrency here.

Differential Reivision: https://reviews.llvm.org/D38481

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@314870 91177308-0d34-0410-b5e6-96231b3b80d8

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