Fixed up intermittently failing tests to skip on Linux.

Also added 'import sys' on some tests that are using non-standard
unittest2.skipUnless blocks with code that is intended to do things
that we have more specializes @* attributes for.  These skip
conditions were failing to execute due to missing import, causing
darwin-only tests to run on Linux regardless.  Will file a bug for
that separately.

llvm-svn: 204747
diff --git a/lldb/test/expression_command/call-restarts/TestCallThatRestarts.py b/lldb/test/expression_command/call-restarts/TestCallThatRestarts.py
index 0eb1b3c..8749738 100644
--- a/lldb/test/expression_command/call-restarts/TestCallThatRestarts.py
+++ b/lldb/test/expression_command/call-restarts/TestCallThatRestarts.py
@@ -27,6 +27,7 @@
         self.call_function()
 
     @dwarf_test
+    @skipIfLinux # llvm.org/pr19246: intermittent failure
     def test_with_dwarf(self):
         """Test calling std::String member function."""
         self.buildDwarf()
diff --git a/lldb/test/functionalities/inferior-crashing/recursive-inferior/TestRecursiveInferior.py b/lldb/test/functionalities/inferior-crashing/recursive-inferior/TestRecursiveInferior.py
index ddc30db..d10eab8 100644
--- a/lldb/test/functionalities/inferior-crashing/recursive-inferior/TestRecursiveInferior.py
+++ b/lldb/test/functionalities/inferior-crashing/recursive-inferior/TestRecursiveInferior.py
@@ -3,6 +3,7 @@
 import os, time
 import unittest2
 import lldb, lldbutil
+import sys
 from lldbtest import *
 
 class CrashingRecursiveInferiorTestCase(TestBase):
@@ -66,6 +67,7 @@
         self.recursive_inferior_crashing_step_after_break()
 
     @skipIfFreeBSD # llvm.org/pr16684
+    @expectedFailureLinux('llvm.org/pr16684')
     def test_recursive_inferior_crashing_step_after_break_dwarf(self):
         """Test that lldb functions correctly after stepping through a crash."""
         self.buildDwarf()
@@ -78,7 +80,7 @@
         self.recursive_inferior_crashing_expr_step_expr()
 
     @expectedFailureFreeBSD('llvm.org/pr15989') # Couldn't allocate space for the stack frame
-    @expectedFailureLinux # llvm.org/pr15989 - Couldn't allocate space for the stack frame
+    @expectedFailureLinux('llvm.org/pr15989') # Couldn't allocate space for the stack frame
     def test_recursive_inferior_crashing_expr_step_and_expr_dwarf(self):
         """Test that lldb expressions work before and after stepping after a crash."""
         self.buildDwarf()
diff --git a/lldb/test/functionalities/step-avoids-no-debug/TestStepNoDebug.py b/lldb/test/functionalities/step-avoids-no-debug/TestStepNoDebug.py
index c3521a3..22f186e 100644
--- a/lldb/test/functionalities/step-avoids-no-debug/TestStepNoDebug.py
+++ b/lldb/test/functionalities/step-avoids-no-debug/TestStepNoDebug.py
@@ -6,6 +6,7 @@
 import re
 import unittest2
 import lldb, lldbutil
+import sys
 from lldbtest import *
 
 class ReturnValueTestCase(TestBase):
@@ -40,6 +41,7 @@
 
     @python_api_test
     @dwarf_test
+    @skipIfLinux # intermittent failure - llvm.org/pr19247
     def test_step_over_with_dwarf_python(self):
         """Test stepping over using avoid-no-debug with dwarf."""
         self.buildDwarf()
@@ -57,6 +59,7 @@
 
     @python_api_test
     @dwarf_test
+    @skipIfLinux # intermittent failure - llvm.org/pr19247
     def test_step_in_with_dwarf_python(self):
         """Test stepping in using avoid-no-debug with dwarf."""
         self.buildDwarf()
diff --git a/lldb/test/macosx/add-dsym/TestAddDsymMidExecutionCommand.py b/lldb/test/macosx/add-dsym/TestAddDsymMidExecutionCommand.py
index e74c37f..1fc8e59 100644
--- a/lldb/test/macosx/add-dsym/TestAddDsymMidExecutionCommand.py
+++ b/lldb/test/macosx/add-dsym/TestAddDsymMidExecutionCommand.py
@@ -4,6 +4,7 @@
 import unittest2
 import lldb
 import pexpect
+import sys
 from lldbtest import *
 
 @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")