Series for -Wunterminated-string-initialization in 6.14 and 6.12

Hi Greg and Sasha,

Please find attatched backports for 6.14 and 6.12 (which have -Wextra enabled by default) to turn off a new warning from -Wextra in GCC 15 and Clang 21, -Wunterminated-string-initialization, which is fatal when CONFIG_WERROR is enabled. Please let me know if there are any issues or questions.

Cheers, Nathan