[Bug libstdc++/58393] Please relax feature check for std::to_string and std::sto* for uClibc

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58393

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
In any case, please send patches to the mailing list, attached to bug report
will be easily overlooked. More specifically, if we are going to be more fine
grained about C99 support, other headers have to be consistently updated.