[J3] Miscount of derived types

[William Clodius]

In my copy of 18-007r1, Section 17.2 begins with the claim "The modules IEEE_EXCEPTIONS, IEEE_ARITHMETIC, and IEEE_FEATURES define five derived types”. By my count they define six derived types: three, IEEE_FLAG_TYPE, IEEE_MODES_TYPE, and IEEE_STATUS_TYPE, in IEEE_EXCEPTIONS; two, IEEE_CLASS_TYPE, and IEEE_ROUND_TYPE, in IEEE_ARITHMETIC, and one, IEEE_FEATURES_TYPE, in IEEE_FEATURES.