Added expectedFlakey test decorator

SUMMARY
Flakey tests get two chances to pass

Also, switched a bunch of tests to use new decorator.

TEST PLAN
Add one of these decorators to a test
Edit a test to pass on the first invocation, confirm test appears as pass
Edit a test to pass on the first invocation, pass on the second, confirm test appears as xfail
Edit a test to fail on two consecutive runs, confirm test appears in results as fail/error

Differential Revision: http://reviews.llvm.org/D10721

llvm-svn: 240789
diff --git a/lldb/test/expression_command/timeout/TestCallWithTimeout.py b/lldb/test/expression_command/timeout/TestCallWithTimeout.py
index 4b13316..4cc5577 100644
--- a/lldb/test/expression_command/timeout/TestCallWithTimeout.py
+++ b/lldb/test/expression_command/timeout/TestCallWithTimeout.py
@@ -28,7 +28,7 @@
         self.call_function()
 
     @expectedFailureFreeBSD("llvm.org/pr19605") # fails on buildbot
-    @expectedFailureLinux("llvm.org/pr20275") # fails intermittently on Linux
+    @expectedFlakeyLinux("llvm.org/pr20275")
     @dwarf_test
     def test_with_dwarf(self):
         """Test calling std::String member function."""