generic: net: add pending wireguard patch to fix build with GCC15

generic: net: add pending wireguard patch to fix build with GCC15

This patch adds __nonstring annotation to address GCC15 with
-Wunterminated-string-initialization.
It is accepted in wireguard-linux in [1] and pending for v6.16
in [2].

[1] https://git.zx2c4.com/wireguard-linux/commit/?h=devel&id=71e5da46e78c1cd24e2feed251a2845327447ad8
[2] https://patch.msgid.link/20250521212707.1767879[email protected]

Signed-off-by: Jonas Jelonek <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/18950
Signed-off-by: Hauke Mehrtens <[email protected]>