SSE min and max instructions. The real thing this code needs to be
concerned about is negative zero.
Update the sse-minmax.ll test accordingly, and add tests for
-enable-unsafe-fp-math mode as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96775 91177308-0d34-0410-b5e6-96231b3b80d8