[boost] [Boost.Config] Stlport patch for Sun compilers on Linux

Hi, I've attached a patch to fix this error with the sun compilers on Linux. http://tinyurl.com/6o4fxg I'm not well versed with the subtleties of Stlport (there may be better ways to code this). The patch merely avoids defining macro BOOST_NO_EXCEPTION_STD_NAMESPACE as the Stlport bundled with the Sun compilers on Linux seems to correctly put all type_info into the std namespace. The Sun compilers on Solaris still require this macro definition. I've tested that this fixes the type_info error with sun-5.9 on Linux and that it doesn't break the Sun tests on Solaris, okay to commit? -- Noel