[mlir][Inliner] Store the resolved call by-value instead of by-reference

[rriddle]

Summary

This avoids asan failures as more calls may be added during inlining, invalidating the reference.

mlir/lib/Transforms/Inliner.cpp

inlineCallsInSCC(Inliner &inliner, CGUseList &useList,
 
   // A set of dead nodes to remove after inlining.
   SmallVector<CallGraphNode *, 1> deadNodes;
 
   // Try to inline each of the call operations. Don't cache the end iterator
   // here as more calls may be added during inlining.
   bool inlinedAnyCalls = false;
   for (unsigned i = 0; i != calls.size(); ++i) {
-    ResolvedCall &it = calls[i];
+    ResolvedCall it = calls[i];
     LLVM_DEBUG({
       llvm::dbgs() << "* Considering inlining call: ";
       it.call.dump();
     });
     if (!shouldInline(it))
       continue;
     CallOpInterface call = it.call;
     Region *targetRegion = it.targetNode->getCallableRegion();