message: Add name_and_version_diff_t
diff: @@ -25,4 +25,15 @@ namespace vcpkg
  std::string toString() const;
  };
  +
  + struct name_and_version_diff_t
  + {
  + static bool compare_by_name(const name_and_version_diff_t& left, const name_and_version_diff_t& right)
  + {
  + return left.name < right.name;
  + }
  +
  + std::string name;
  + version_diff_t version_diff;
  + };
  }
  