Fix missed out llvm-stress after APFloat change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173141 91177308-0d34-0410-b5e6-96231b3b80d8
ADT/SparseMultiSetTest.cpp: Try to appease cygwin-clang on stage2, take two. [-Wsign-compare]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173144 91177308-0d34-0410-b5e6-96231b3b80d8