[lldb/test] Skip editline tests when LLDB_ENABLE_LIBEDIT is off.

Add a new decorator that checks if LLDB was build with editline support
and mark the relevant tests as skipped when that's not the case.

lldb/packages/Python/lldbsuite/test/commands/expression/multiline-completion/TestMultilineCompletion.py

@@ -15,6 +15,7 @@ class MultilineCompletionTest(PExpectTest):
     # under ASAN on a loaded machine..
     @skipIfAsan
     @skipIfRemote  # test is written to explicitly "run" the binary
+    @skipIfEditlineSupportMissing
     def test_basic_completion(self):
         """Test that we can complete a simple multiline expression"""
         self.build()

lldb/packages/Python/lldbsuite/test/commands/expression/multiline-navigation/TestMultilineNavigation.py

@@ -17,6 +17,7 @@ class TestCase(PExpectTest):
     # PExpect uses many timeouts internally and doesn't play well
     # under ASAN on a loaded machine..
     @skipIfAsan
+    @skipIfEditlineSupportMissing
     def test_nav_arrow_up(self):
         """Tests that we can navigate back to the previous line with the up arrow"""
         self.launch()
@@ -38,6 +39,7 @@ class TestCase(PExpectTest):
         self.quit()
 
     @skipIfAsan
+    @skipIfEditlineSupportMissing
     def test_nav_arrow_down(self):
         """Tests that we can navigate to the next line with the down arrow"""
         self.launch()

lldb/packages/Python/lldbsuite/test/decorators.py

@@ -808,6 +808,9 @@ def skipIfCursesSupportMissing(func):
 def skipIfXmlSupportMissing(func):
     return _get_bool_config_skip_if_decorator("xml")(func)
 
+def skipIfEditlineSupportMissing(func):
+    return _get_bool_config_skip_if_decorator("editline")(func)
+
 def skipIfLLVMTargetMissing(target):
     config = lldb.SBDebugger.GetBuildConfiguration()
     targets = config.GetValueForKey("targets").GetValueForKey("value")

lldb/packages/Python/lldbsuite/test/iohandler/completion/TestIOHandlerCompletion.py

@@ -16,6 +16,7 @@ class IOHandlerCompletionTest(PExpectTest):
     # PExpect uses many timeouts internally and doesn't play well
     # under ASAN on a loaded machine..
     @skipIfAsan
+    @skipIfEditlineSupportMissing
     def test_completion(self):
         self.launch(dimensions=(100,500))
 

lldb/packages/Python/lldbsuite/test/terminal/TestEditline.py

@@ -16,6 +16,7 @@ class EditlineTest(PExpectTest):
     mydir = TestBase.compute_mydir(__file__)
 
     @skipIfAsan
+    @skipIfEditlineSupportMissing
     def test_left_right_arrow(self):
         """Test that ctrl+left/right arrow navigates words correctly.