[MLIR][OpenMP] Replace index-based loop (NFC) (llvm#107878)

Author: skatrak

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -3428,14 +3428,12 @@ convertOmpTarget(Operation &opInst, llvm::IRBuilderBase &builder,
       llvmOutlinedFn->addFnAttr(attr);
 
     builder.restoreIP(codeGenIP);
-    unsigned argIndex = 0;
-    for (auto &mapOp : mapVars) {
+    for (auto [argIndex, mapOp] : llvm::enumerate(mapVars)) {
       auto mapInfoOp = cast<omp::MapInfoOp>(mapOp.getDefiningOp());
       llvm::Value *mapOpValue =
           moduleTranslation.lookupValue(mapInfoOp.getVarPtr());
       const auto &arg = targetRegion.front().getArgument(argIndex);
       moduleTranslation.mapValue(arg, mapOpValue);
-      argIndex++;
     }
     llvm::BasicBlock *exitBlock = convertOmpOpRegions(
         targetRegion, "omp.target", builder, moduleTranslation, bodyGenStatus);