[Bug c/116082] -Wunterminated-string-initialization should not warn about strings that end with "\0" but should warn still for -Wc++-compat

[steffen at sdaoden dot eu via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116082

Steffen Nurpmeso <steffen at sdaoden dot eu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steffen at sdaoden dot eu

--- Comment #4 from Steffen Nurpmeso <steffen at sdaoden dot eu> ---
Hello.

I just now compiled 15.1.0 (on Linux) and i get the same warnings, for example

```
/home/steffen/src/nail.git/src/mx/cmd-vexpr.c:170:50: warning:
initializer-string for array of 'char' truncates NUL terminator but destination
lacks 'nonstring' attribute (16 chars into 15 av
ailable) [-Wunterminated-string-initialization]
  170 |         {a_X(a_VEXPR_CMD_AGN_DATE_STAMP_UTC, 0), "date-stamp-utc\0"},
      |                                                  ^~~~~~~~~~~~~~~~~~
```

This always worked for many years.
That is, i add \0 (to long ones) to ensure that the buffer is large enough.
Until now the compiler was silent because the char is NUL terminated anyway,
but now the above false (it is NUL terminated) warning occurs.

Thanks,