package/libbpf: needs headers >= 4.13

package/libbpf: needs headers >= 4.13

Since its addition in commit f7b8508e4fe9c96bf679cc5423cc1500b6523e83,
libbpf unconditionally uses TCA_BPF_ID which is only available since
kernel 4.13 and
https://github.com/torvalds/linux/commit/e86283071fb0eed28136adb52997888f4beb202b:

netlink.c: In function '__get_tc_info':
netlink.c:515:11: error: 'TCA_BPF_ID' undeclared (first use in this function); did you mean 'TCA_BPF_FD'?
  515 |  if (!tbb[TCA_BPF_ID])
      |           ^~~~~~~~~~
      |           TCA_BPF_FD

Fixes:
 - http://autobuild.buildroot.org/results/14996a0b7b9b65d0d6d5717d6da8922752789749

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>