[Orc] Fix iterator usage after remove

[aganea]

Summary

The test [OrcJITTests]CoreAPIsStandardTest.FailureInDependency previously failed on a Debug build on Windows with _ITERATOR_DEBUG_LEVEL == 2. This was caused by the collection being iterated (MII->second.pendingQueries()) to be modified in JITDylib::MaterializingInfo::removeQuery() (called by Q->detach()).

[lhames]

LGTM. Thanks Alexandre!

llvm/lib/ExecutionEngine/Orc/Core.cpp

while (!Worklist.empty()) {
           UnemittedDepMII->second.Dependants[&JD].erase(Name);
           if (UnemittedDepMII->second.Dependants[&JD].empty())
             UnemittedDepMII->second.Dependants.erase(&JD);
         }
       }
       MI.UnemittedDependencies.clear();
 
       // Collect queries to be failed for this MII.
+      AsynchronousSymbolQueryList ToDetach;
       for (auto &Q : MII->second.pendingQueries()) {
         // Add the query to the list to be failed and detach it.
         FailedQueries.insert(Q);
-        Q->detach();
+        ToDetach.push_back(Q);
       }
+      for (auto &Q : ToDetach)
+        Q->detach();
 
       assert(MI.Dependants.empty() &&
              "Can not delete MaterializingInfo with dependants still attached");
       assert(MI.UnemittedDependencies.empty() &&
              "Can not delete MaterializingInfo with unemitted dependencies "
              "still attached");
       assert(!MI.hasQueriesPending() &&
              "Can not delete MaterializingInfo with queries pending");