Revert "[ValueTracking] Drop ucmp/scmp from getIntrinsicRange() (NFCI)"

This does seem to cause some functionality to change, see comment on
llvm@278c429

This reverts commit 278c429.

Author: zmodem

llvm/lib/Analysis/ValueTracking.cpp

@@ -10146,6 +10146,10 @@ static ConstantRange getRangeForIntrinsic(const IntrinsicInst &II,
     if (!II.getParent() || !II.getFunction())
       break;
     return getVScaleRange(II.getFunction(), Width);
+  case Intrinsic::scmp:
+  case Intrinsic::ucmp:
+    return ConstantRange::getNonEmpty(APInt::getAllOnes(Width),
+                                      APInt(Width, 2));
   default:
     break;
   }