Implement builtins for safe division: safe.sdiv.iN, safe.udiv.iN, safe.srem.iN,
safe.urem.iN (iN = i8, i16, i32, or i64).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206732 91177308-0d34-0410-b5e6-96231b3b80d8