bpftool: Update to version 7.1.0

bpftool: Update to version 7.1.0

bpftool changelog: https://github.com/libbpf/bpftool/releases
libbpf changelog: https://github.com/libbpf/libbpf/releases

This updates the bfptool to version 7.1.0. This also includes an update
of the libbpf to version 1.1.

This also adds some new feature options and removes some old ones which
were also removed form the source code. zlib for example is now
mandatory.

Add -flto also to LD flags to make it really work.

Before this change bpftool was on a git commit between version 6.7 and
6.8 and libbpf was on a commit between version 0.7 and 0.8.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>