[lldb] [test] Mark failing tests XFAIL on NetBSD

Add a convenience 'expectedFailureNetBSD' decorator and mark all tests
currently failing on NetBSD with it.  Also skip a few tests that hang
the test suite.  This should establish a baseline for the test suite
and get us closer to enabling tests on buildbot.  This will help us
catch regressions while we still have a lot of work to do to get tests
working.

It seems that there are also some flaky tests.  I am going to address
them later on.

Differential Revision: https://reviews.llvm.org/D58527

llvm-svn: 355320

lldb/packages/Python/lldbsuite/test/python_api/thread/TestThreadAPI.py

@@ -42,6 +42,7 @@ class ThreadAPITestCase(TestBase):
     @add_test_categories(['pyapi'])
     @expectedFailureAll(oslist=['freebsd'], bugnumber='llvm.org/pr20476')
     @expectedFailureAll(oslist=["windows"])
+    @expectedFailureNetBSD
     def test_step_out_of_malloc_into_function_b(self):
         """Test Python SBThread.StepOut() API to step out of a malloc call where the call site is at function b()."""
         # We build a different executable than the default build() does.