gets with C++ and GCC before 4.7

[Roland McGrath]

> As I understand it, the libstdc++ maintainers would prefer to have gets 
> declarations for C++ up to and including C++11, following the C++ 
> standard, and only disable the declaration in a future C++17 mode.  That 
> is, the state immediately after my commit 
> 8ecd6b2a1283a28bcf56cfe48099fafa412a3929 would be preferable to them, and 
> from their point of view no such macro would need to be defined because 
> C++17 mode would use a newer __cplusplus value to disable the declaration.

If C++11 says that #include <stdio.h> should declare gets regardless
of things like feature-test macros, then it seems pretty cut and dry.


Thanks,
Roland