Fix build failure revealed by c35ca3a

This commit resolves a Linux kernel build failure that was revealed by
c35ca3a. The patch introduces two new
intrinsics, which ultimately changes the intrinsic numbering of other PPC
intrinsics. This causes an issue introduced by
ff40fb0, as the patch checks for intrinsics
with particular values, but the addition of the fnabs/fnabss intrinsics updates
the original sqrt/sdiv intrinsic values.

Author: amy-kwan

llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp

@@ -4646,7 +4646,8 @@ static bool mayUseP9Setb(SDNode *N, const ISD::CondCode &CC, SelectionDAG *DAG,
 static bool isSWTestOp(SDValue N) {
   if (N.getOpcode() == PPCISD::FTSQRT)
     return true;
-  if (N.getNumOperands() < 1 || !isa<ConstantSDNode>(N.getOperand(0)))
+  if (N.getNumOperands() < 1 || !isa<ConstantSDNode>(N.getOperand(0)) ||
+      N.getOpcode() != ISD::INTRINSIC_WO_CHAIN)
     return false;
   switch (N.getConstantOperandVal(0)) {
   case Intrinsic::ppc_vsx_xvtdivdp: