Revert: [APFloat] Fixed a bug in method 'fusedMultiplyAdd'.

This reverts revision 216913; the new test added at revision 216913
caused regression failures on a couple of buildbots.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216914 91177308-0d34-0410-b5e6-96231b3b80d8