Fix bug causing FileSpec::GetPath() to crash with a null dest.
Fix bug causing FileSpec::GetPath() to crash with a null dest.

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@215262 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb