[lldb-tests] Add libcxx version check for regex tests

[fdeazeve]

Summary

Regex requires the c++20 flag, which was not introduced available prior
to Clang 11.

lldb/test/API/functionalities/step-avoids-regexp/TestStepAvoidsRegexp.py

def hit_correct_function(self, pattern):
             (name, pattern))
 
     def setUp(self):
         TestBase.setUp(self)
         self.dbg.HandleCommand(
                 "settings set target.process.thread.step-avoid-regexp ^ignore::")
 
     @skipIfWindows
+    @skipIf(compiler="clang", compiler_version=['<', '11.0'])
     def test_step_avoid_regex(self):
         """Tests stepping into a function which matches the avoid regex"""
         self.build()
         (_, _, self.thread, _) = lldbutil.run_to_source_breakpoint(self, "main", lldb.SBFileSpec('main.cpp'))
 
         # Try to step into ignore::auto_ret
         self.thread.StepInto()
         self.hit_correct_function("main")
 
         # Try to step into ignore::with_tag
         self.thread.StepInto()
         self.hit_correct_function("main")
 
         # Try to step into ignore::decltype_auto_ret
         self.thread.StepInto()
         self.hit_correct_function("main")
 
     @skipIfWindows
+    @skipIf(compiler="clang", compiler_version=['<', '11.0'])
     @expectedFailureAll(bugnumber="rdar://100645742")
     def test_step_avoid_regex_abi_tagged_template(self):
         """Tests stepping into an ABI tagged function that matches the avoid regex"""
         self.build()
         (_, _, self.thread, _) = lldbutil.run_to_source_breakpoint(self, "with_tag_template", lldb.SBFileSpec('main.cpp'))
 
         # Try to step into ignore::with_tag_template
         self.thread.StepInto()
         self.hit_correct_function("main")