Build fix for Boost 1.56

fixes #7001

lib/base/array.hpp

@@ -22,6 +22,7 @@
 
 #include "base/i2-base.hpp"
 #include "base/value.hpp"
+#include <boost/range/iterator.hpp>
 #include <vector>
 
 namespace icinga

lib/base/dictionary.hpp

@@ -23,6 +23,7 @@
 #include "base/i2-base.hpp"
 #include "base/object.hpp"
 #include "base/value.hpp"
+#include <boost/range/iterator.hpp>
 #include <map>
 
 namespace icinga

lib/base/qstring.hpp

@@ -21,6 +21,7 @@
 #define STRING_H
 
 #include "base/i2-base.hpp"
+#include <boost/range/iterator.hpp>
 #include <string.h>
 #include <functional>
 #include <string>
@@ -173,16 +174,12 @@ struct string_iless : std::binary_function<String, String, bool>
 namespace boost
 {
 
-template <typename C> struct range_mutable_iterator;
-
 template<>
 struct range_mutable_iterator<icinga::String>
 {
 	typedef icinga::String::Iterator type;
 };
 
-template <typename C> struct range_const_iterator;
-
 template<>
 struct range_const_iterator<icinga::String>
 {