http://xyst.i2p/libstdcpp_license_page.html
Hopefully that text is self-explanatory. If it isn't, you need to speak to your lawyer, or the Free Software Foundation.
The Documentation: GPL, FDL
The documentation shipped with the library and made available over the web, excluding the pages generated from source comments, are copyrighted by the Free Software Foundation, and placed under the GNU Free Documentation License version 1.3.