Add out-of-line copy ctor to Maps::Iterator.

maps.cc

Index: maps.cc
===================================================================
--- maps.cc	(revision 186)
+++ maps.cc	(working copy)
@@ -112,6 +112,13 @@
       at_end_(at_end) {
 }
 
+Maps::Iterator::Iterator(const Iterator& other)
+    : iter_(other.iter_),
+      maps_(other.maps_),
+      at_beginning_(other.at_beginning_),
+      at_end_(other.at_end_) {
+}
+
 Maps::LibraryMap::iterator& Maps::Iterator::getIterator() const {
   if (at_beginning_) {
     iter_ = maps_->libs_.begin();