[boost][range] - Merge a fix to undo an erroneous change to iterator_range.size() that allowed it to compile for ranges that did not model the Random Access Range Concept and thereby broken the complexity guarantees.

[SVN r68190]

include/boost/range/iterator_range_core.hpp

@@ -231,7 +231,7 @@ namespace boost
 
             difference_type size() const
             {
-                return std::distance(m_Begin, m_End);
+				return m_End - m_Begin;
             }
 
             bool empty() const