[flang[mlir] Fix-forward heap use-after-free in llvm#155348

mapInfoOp should not be accessed here because cloneModifyAndErase (line 255) erased it. Fix the issue by replacing mapInfoOp with the cloned op.

Author: thurstond

mlir/lib/Dialect/OpenMP/Transforms/OpenMPOffloadPrivatizationPrepare.cpp

@@ -252,7 +252,8 @@ class PrepareForOMPOffloadPrivatizationPass
         // variable, rewrite all the uses of the original variable with
         // the heap-allocated variable.
         rewriter.setInsertionPoint(targetOp);
-        rewriter.setInsertionPoint(cloneModifyAndErase(mapInfoOp));
+        mapInfoOp = cloneModifyAndErase(mapInfoOp);
+        rewriter.setInsertionPoint(mapInfoOp);
 
         // Fix any members that may use varPtr to now use heapMem
         for (auto member : mapInfoOp.getMembers()) {