[ARM] Optimize {s,u}{add,sub}.with.overflow.

The AArch64 backend contains code to optimize {s,u}{add,sub}.with.overflow during SelectionDAG.  This commit ports that code to the ARM backend.

Differential revision: https://reviews.llvm.org/D35635

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321224 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed