Find and allows users to use the cached SDK's that might be in...

Find and allows users to use the cached SDK's that might be in "~/Library/Developer/Xcode/iOS DeviceSupport".
Also enabled PlatformRemoteiOS to select an SDK using the build number in case you have mutliple 5.0 SDKs installed:

(lldb) platform select remote-ios --build 11C123

llvm-svn: 154978