auto/cc: gcc: Don't disable -Wunterminated-string-initialization

Now that we are able to use the "nonstring" variable attribute to quell
this warning, we no longer need to disable it.

The good thing is there was never a released version of GCC where the
warning couldn't be quelled by the attribute.

Fixes: 1503782 ("Fix build with GCC 15")
Cc: Alejandro Colomar <alx@kernel.org>
Reviewed-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

Author: ac000

auto/cc/test

@@ -93,10 +93,6 @@ case $NXT_CC_NAME in
 
         NXT_CFLAGS="$NXT_CFLAGS -Wmissing-prototypes"
 
-        # Disable Wunterminated-string-initialization temporarily.
-        # See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178#c21>
-        NXT_CFLAGS="$NXT_CFLAGS -Wno-unterminated-string-initialization"
-
         # Stop on warning.
         NXT_CFLAGS="$NXT_CFLAGS -Werror"