std::string overloads for xfstream

[Paolo Carlini]

... as committed. Tested x86_64-linux.

Paolo.

/////////////////////////
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: CL_ed
URL: <http://gcc.gnu.org/pipermail/libstdc++/attachments/20090325/b17968f2/attachment.ksh>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: patch_ed
URL: <http://gcc.gnu.org/pipermail/libstdc++/attachments/20090325/b17968f2/attachment-0001.ksh>