[SchedModel] Use std::move to replace a vector instead of vector::swap

We don't really care about the old vector value so we don't care to swap it.

llvm-svn: 328440

llvm/utils/TableGen/CodeGenSchedule.cpp

@@ -710,7 +710,7 @@ unsigned CodeGenSchedModels::addSchedClass(Record *ItinClassDef,
                    SchedClasses[Idx].ProcIndices.end(),
                    ProcIndices.begin(), ProcIndices.end(),
                    std::back_inserter(PI));
-    SchedClasses[Idx].ProcIndices.swap(PI);
+    SchedClasses[Idx].ProcIndices = std::move(PI);
     return Idx;
   }
   Idx = SchedClasses.size();