use strstream only when BOOST_NO_STRINGSTREAM is defined
this avoids deprecated-warnings on gcc 3.1

svn path=/trunk/boost/libs/any/; revision=13986
Add parens to quiet warning

svn path=/trunk/boost/libs/any/; revision=14583
Workarounds for SunPro CC

svn path=/trunk/boost/libs/any/; revision=16493