[ARM] Enable SETCCCARRY lowering for Thumb1.

We've had Thumb1 support for ARMISD::SUBE for a while now, so this just
works.  Reduces codesize a bit for 64-bit integer comparisons.

Differential Revision: https://reviews.llvm.org/D47387



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333445 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed