[TestEvents] Replace expectedFailureLinux with skipIfLinux

[sivachandra]

Summary

If we do not mark them as skip, they are still executed, which in
turn is leading to an assertion failure. The change also adds
skipIfLinux to a testlet which was not previously marked with
skipIfLinux. This is because running even that test let leads to an
assertion failure.

test/python_api/event/TestEvents.py

class EventAPITestCase(TestBase):
     @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
     @python_api_test
     @dsym_test
     def test_listen_for_and_print_event_with_dsym(self):
         """Exercise SBEvent API."""
         self.buildDsym()
         self.do_listen_for_and_print_event()
 
+    @unittest2.skipUnless((sys.platform.startswith("darwin") or
+                           sys.platform.startswith("freebsd")),
+                          "requires Darwin or FreeBSD")
     @python_api_test
     @dwarf_test
     def test_listen_for_and_print_event_with_dwarf(self):
         """Exercise SBEvent API."""
         self.buildDwarf()
         self.do_listen_for_and_print_event()
 
     @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
     @python_api_test
     @dsym_test
     def test_wait_for_event_with_dsym(self):
         """Exercise SBListener.WaitForEvent() API."""
         self.buildDsym()
         self.do_wait_for_event()
 
-    @expectedFailureLinux # non-core functionality, need to reenable and fix later (DES 2014.11.07)
+    @skipIfLinux # non-core functionality, need to reenable and fix later (DES 2014.11.07)
     @python_api_test
     @dwarf_test
     def test_wait_for_event_with_dwarf(self):
         """Exercise SBListener.WaitForEvent() API."""
         self.buildDwarf()
         self.do_wait_for_event()
 
     @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
     @python_api_test
     @dsym_test
     def test_add_listener_to_broadcaster_with_dsym(self):
         """Exercise some SBBroadcaster APIs."""
         self.buildDsym()
         self.do_add_listener_to_broadcaster()
 
     @skipIfFreeBSD # llvm.org/pr21325
-    @expectedFailureLinux # non-core functionality, need to reenable and fix later (DES 2014.11.07)
+    @skipIfLinux # non-core functionality, need to reenable and fix later (DES 2014.11.07)
     @python_api_test
     @dwarf_test
     def test_add_listener_to_broadcaster_with_dwarf(self):
         """Exercise some SBBroadcaster APIs."""
         self.buildDwarf()
         self.do_add_listener_to_broadcaster()
 
     def setUp(self):