Merge branch 'bpftool_sockmap'

John Fastabend says:

====================
The first patch adds support for attaching programs to maps. This is
needed to support sock{map|hash} use from bpftool. Currently, I carry
around custom code to do this so doing it using standard bpftool will
be great.

The second patch adds a compat mode to ignore non-zero entries in
the map def. This allows using bpftool with maps that have a extra
fields that the user knows can be ignored. This is needed to work
correctly with maps being loaded by other tools or directly via
syscalls.

v3: add bash completion and doc updates for --mapcompat
====================

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