[boost] [iterator] Make operators conditionally defined

Subject: [boost] [iterator] Make operators conditionally defined
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2014-06-30 03:40:07

Hi,

I've made this pull request:

https://github.com/boostorg/iterator/pull/4

which makes operators defined for iterator_facade conditionally defined 
depending on the iterator category. As a side effect this change fixes 
Boost.Graph tests broken by the recent change to boost::next()/prior() [1].

Could someone take a look and merge it?

[1] http://lists.boost.org/Archives/boost/2014/06/214788.php