tools: elfutils: set -std=gnu17

tools: elfutils: set -std=gnu17

Fedora 42 updated to GCC15 which now defaults to GNU23 as the default
instead of GNU17[1], and this breaks m4 compilation.

This looks like a gnulib issue, so until that is updated/fixed
lets simply set C language version back to GNU17.

[1] https://gcc.gnu.org/gcc-15/porting_to.html#c23

Link: https://github.com/openwrt/openwrt/pull/18506
(cherry picked from commit f165dd2f78f7aaafa85f59f5c35264dd03e3a6ce)
Link: https://github.com/openwrt/openwrt/pull/18581
Signed-off-by: Robert Marko <robimarko@gmail.com>
[Rework patch to make it apply]
(cherry picked from commit 1e51fd037d780725ca31cc92b39078468a383295)
Link: https://github.com/openwrt/openwrt/pull/19065
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>