message: [lldb] Use the new Regex::isValid() with no parameter
diff: @@ -28,10 +28,7 @@ bool RegularExpression::Execute(
  return m_regex.match(str, matches);
  }
  -bool RegularExpression::IsValid() const {
  - std::string discarded;
  - return m_regex.isValid(discarded);
  -}
  +bool RegularExpression::IsValid() const { return m_regex.isValid(); }
  llvm::StringRef RegularExpression::GetText() const { return m_regex_text; }
  