add required directories to the path automatically, so the user doesn't need to worry about it.
add required directories to the path automatically, so the user doesn't need to worry about it.


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@39901 91177308-0d34-0410-b5e6-96231b3b80d8

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