[boost] [graph] fix for intel-win32-7.1-vc6

This trivial fix takes care of issues having to do with BOOST_NO_STDC_NAMESPACE, which impact the test layout_test on intel-win32-7.1-vc6. OK to commit? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo 106a107

#ifndef BOOST_NO_STDC_NAMESPACE 107a109 #endif // BOOST_NO_STDC_NAMESPACE 126a129 #ifndef BOOST_NO_STDC_NAMESPACE 127a131 #endif // BOOST_NO_STDC_NAMESPACE 145a150 #ifndef BOOST_NO_STDC_NAMESPACE 146a152 #endif // BOOST_NO_STDC_NAMESPACE