[APFloat] Fix comments. NFC.

Summary: Fix comments in response to jlebar's comments in D27872.

Reviewers: jlebar

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29109

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293116 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed