Add an explicit check for a darwin kernel KDP_VERSIONSTRING when
starting a kdp communication session, instead of assuming darwin
kernel for any "non-EFI" kdp session.
<rdar://problem/13854098>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@181566 91177308-0d34-0410-b5e6-96231b3b80d8