libstdc++/6718: Boost1.28 run-time problem

[Nathan Sidwell]

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6718

this is a libstdc++ issue. <limits> appears to specialize
template<> struct numeric_limits<double> to

     static double infinity() throw()
       { return __glibcpp_double_infinity; }

and earlier,
#ifndef __glibcpp_double_infinity
#define __glibcpp_double_infinity 0.0
#endif

on the mainline this is significantly different, using __builtin_huge_val.

nathan