Fix Windows build after r159281: s/iterator/const_iterator

llvm-svn: 159334
diff --git a/llvm/utils/TableGen/DFAPacketizerEmitter.cpp b/llvm/utils/TableGen/DFAPacketizerEmitter.cpp
index d97297f..8bfecea 100644
--- a/llvm/utils/TableGen/DFAPacketizerEmitter.cpp
+++ b/llvm/utils/TableGen/DFAPacketizerEmitter.cpp
@@ -262,7 +262,7 @@
 // be added to the packet represented by this state.
 //
 bool State::canAddInsnClass(unsigned InsnClass) const {
-  for (std::set<unsigned>::iterator SI = stateInfo.begin();
+  for (std::set<unsigned>::const_iterator SI = stateInfo.begin();
        SI != stateInfo.end(); ++SI) {
     if (~*SI & InsnClass)
       return true;