tools: ynl: build archives with $(AR)
Use $(AR) to allow build system to override the archiver tool (e.g.,
when cross-compiling for a different architecture) by setting the AR
environment variable.
GNU Make defaults AR to ar, so this change will not break existing build
environments that do not explicitly set AR.
Fixes: 07c3cc51a085 ("tools: net: package libynl for use in selftests")
Fixes: 86878f14d71a ("tools: ynl: user space helpers")
Signed-off-by: Greg Thelen <gthelen@google.com>
Link: https://patch.msgid.link/20260622161659.145047-1-gthelen@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>