[AArch32] Add support for FP rounding operations for ARMv8/AArch32.
Phabricator Revision: http://reviews.llvm.org/D4935

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215772 91177308-0d34-0410-b5e6-96231b3b80d8