Merge branch 'bpf/bpftool: add program & link type names'

Milan Landaverde says:

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

With the addition of the syscall prog type we should now
be able to see feature probe info for that prog type:

    $ bpftool feature probe kernel
    ...
    eBPF program_type syscall is available
    ...
    eBPF helpers supported for program type syscall:
        ...
        - bpf_sys_bpf
        - bpf_sys_close

And for the link types, their names should aid in
the output.

Before:
    $ bpftool link show
    50: type 7  prog 5042
	    bpf_cookie 0
	    pids vfsstat(394433)

After:
    $ bpftool link show
    57: perf_event  prog 5058
	    bpf_cookie 0
	    pids vfsstat(394725)
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>