message: Try to fix old-GCC issue
  Summary:
  Pull Request resolved:
  Make a method static. Capture `this` for another.
diff: @@ -1461,13 +1461,13 @@ class EnumTransformer final {
  always_assert(values_field);
  auto& dmethods = enum_cls->get_dmethods();
  // Delete <init>, values() and valueOf(String) methods, and clean <clinit>.
  - std20::erase_if(dmethods, [&](auto it) {
  + std20::erase_if(dmethods, [&, this](auto it) {
  auto method = *it;
  if (method::is_clinit(method)) {
  clean_clinit(enum_constants, enum_cls, method, values_field);
  return empty(method->get_code());
  }
  - return is_generated_enum_method(method);
  + return this->is_generated_enum_method(method);
  });
  }
  @@ -1552,7 +1552,7 @@ class EnumTransformer final {
  /**
  * Only use for <clinit> code.
  */
  - bool empty(IRCode* code) {
  + static bool empty(IRCode* code) {
  auto iterable = InstructionIterable(code);
  auto begin = iterable.begin();
  return opcode::is_return_void(begin->insn->opcode());
  