Added code to the unittest for APFloat::getSmallest to double check that we consider the result to be denormal.

I additionally changed certain checks to use EXPECT_FALSE instead of a boolean
complement with EXPECT_TRUE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182896 91177308-0d34-0410-b5e6-96231b3b80d8
Added a unittest for APFloat::getSmallestNormalized.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182897 91177308-0d34-0410-b5e6-96231b3b80d8