Merge branch 'bpftool: Add autoattach for bpf prog load|loadall'

Merge branch 'bpftool: Add autoattach for bpf prog load|loadall'

Wang Yufen says:

====================

This patchset add "autoattach" optional for "bpftool prog load(_all)" to support
one-step load-attach-pin_link.

v8 -> v9: fix link leak, and change pathname_concat(specify not just buffer
	  pointer, but also it's size)
v7 -> v8: for the programs not supporting autoattach, fall back to reguler pinning
	  instead of skipping
v6 -> v7: add info msg print and update doc for the skip program
v5 -> v6: skip the programs not supporting auto-attach,
	  and change optional name from "auto_attach" to "autoattach"
v4 -> v5: some formatting nits of doc
v3 -> v4: rename functions, update doc, bash and do_help()
v2 -> v3: switch to extend prog load command instead of extend perf
v2: https://patchwork.kernel.org/project/netdevbpf/patch/20220824033837.458197-1-weiyongjun1@huawei.com/
v1: https://patchwork.kernel.org/project/netdevbpf/patch/20220816151725.153343-1-weiyongjun1@huawei.com/
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>