gcc:
* doc/include/fdl.texi: Move to GFDL version 1.3.
* doc/cpp.texi: Move to GFDL version 1.3.
* doc/gcc.texi: Move to GFDL version 1.3. Fix copyright years.
* doc/gccint.texi: Move to GFDL version 1.3.
* doc/gcov.texi: Move to GFDL version 1.3. Update copyright years.
* doc/install.texi: Move to GFDL version 1.3. Fix copyright years.
* doc/invoke.texi: Move to GFDL version 1.3.