[PATCH] Introduce llvm::sys::path::home_directory.

[Yaron Keren]

  SHGetFolderPath is Deprecated function, Microsoft suggests to use SHGetKnownFolderPath instead.

   http://msdn.microsoft.com/en-us/library/windows/desktop/bb762181(v=vs.85).aspx

  In any case, the easy way to get the AppData directory is getenv("LOCALAPPDATA").

http://llvm-reviews.chandlerc.com/D2199