Added the ability to get the SDK path for a target using the platform plugins. If LLDB lives inside an Xcode.app bundle, it will select the SDK in the Xcode bundle, else it will use the currently selected Xcode.

Also added the DWARFDataExtractor classes to the Xcode project file.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@193380 91177308-0d34-0410-b5e6-96231b3b80d8