Mark Radar9974002DataFormatterTestCase test XFAIL on Linux.

See http://llvm.org/bugs/show_bug.cgi?id=20232 for details.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@212489 91177308-0d34-0410-b5e6-96231b3b80d8