libstdc++: Disable gc-sections to work around binutils bug

I don't think this should go into mainline, as this is a workaround usefull only for released source code.

This is to work around the following error message:
BFD (GNU Binutils) 2.23.2 assertion fail elf32-arc.c:2140

Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
Signed-off-by: Anton Kolesov <anton.kolesov@synopsys.com>