Small cleanup: Don't duplicate default behavior.
Small cleanup: Don't duplicate default behavior.

std::unique_ptr is null initialized and reset default to null.

Thanks to David Blaikie for noticing.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@215560 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang