[boost] [iostreams] fix for vc-6_5

Recent changes to boost/iostreams/positioning.hpp cause VC 6.5 to fail as for instance in http://tinyurl.com/jkdhx . The simple problem is that Dinkum lib for this compiler does not define fpos_t in namespace std, only as a global type. The attached patch just reverts to global ::fpos_t under the aforementioned circumstances. Is there any objection to my commiting to trunk and RC_1_34_0? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo 16a17

#include <boost/config.hpp> 17a19 #include <boost/detail/workaround.hpp> 48a51,53 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) && defined(BOOST_DINKUMWARE_STDLIB) inline stream_offset fpos_t_to_offset(::fpos_t pos) #else 49a55 #endif