tools: cpio: fix compilation with GCC15

tools: cpio: fix compilation with GCC15

Fedora 42 updated to GCC15 which now defaults to GNU23 as the default
instead of GNU17[1], and this breaks cpio compilation.

Its been reported upstream [2], so import the patch attached to the bug
report that fixes compilation with GCC15.

[1] https://gcc.gnu.org/gcc-15/porting_to.html#c23
[2] https://savannah.gnu.org/bugs/?66297

Link: https://github.com/openwrt/openwrt/pull/18506
Signed-off-by: Robert Marko <robimarko@gmail.com>
(cherry picked from commit c5041094ba06b3cdfb9458f1cb5acb00a9cbacd3)
Link: https://github.com/openwrt/openwrt/pull/19065
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>