XFAIL TestMultithreaded on linux

Test sometimes fails even during the reruns, upgrading to xflaky to xfail.

llvm-svn: 257068

lldb/packages/Python/lldbsuite/test/api/multithreaded/TestMultithreaded.py

@@ -51,7 +51,7 @@ class SBBreakpointCallbackCase(TestBase):
     @skipIfNoSBHeaders
     @skipIfWindows # clang-cl does not support throw or catch (llvm.org/pr24538)
     @expectedFlakeyFreeBSD
-    @expectedFlakeyLinux
+    @expectedFailureLinux
     def test_sb_api_listener_resume(self):
         """ Test that a process can be resumed from a non-main thread. """
         self.build_and_test('driver.cpp listener_test.cpp test_listener_resume.cpp',