message: [lldb] Remove unused method declaration
  FindCompleteObjCDefinitionType is not used anywhere and there is no implementation of it, only a declaration.
  Test plan: make check-lldb
diff: @@ -396,10 +396,6 @@ protected:
  const DWARFDIE &die, const lldb_private::ConstString &type_name,
  bool must_be_implementation);
  - lldb::TypeSP
  - FindCompleteObjCDefinitionType(const lldb_private::ConstString &type_name,
  - bool header_definition_ok);
  -
  lldb_private::Symbol *
  GetObjCClassSymbol(const lldb_private::ConstString &objc_class_name);
  