Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes (bug 34579)

Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes to behave correctly in the case that the size of the significand is a multiple of the width of the integerParts making up the significand.

The patch to IEEEFloat::isSignificandAllOnes fixes bug 34579, and the patch to IEEE:Float:isSignificandAllZeros fixes the unit test "APFloatTest.x87Next" I added here. I have included both in this diff since the changes are very similar.

Patch by Andrew Briand