[Bug libstdc++/57212] Don't use pe-coff weak support with mingw

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57212

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2013-05-08 15:11:53 UTC ---
Thanks Kai, please commit the patch with an appropriate ChangeLog entry
mainline and 4_8-branch. Please also send it to gcc-patches.