Merge branch 'xskmap-lookup'

Jonathan Lemon says:

====================
Currently, the AF_XDP code uses a separate map in order to
determine if an xsk is bound to a queue.  Have the xskmap
lookup return a XDP_SOCK pointer on the kernel side, which
the verifier uses to extract relevant values.

Patches:
 1 - adds XSK_SOCK type
 2 - sync bpf.h with tools
 3 - add tools selftest
 4 - update lib/bpf, removing qidconf

v4->v5:
 - xskmap lookup now returns XDP_SOCK type instead of pointer to element.
 - no changes lib/bpf/xsk.c

v3->v4:
 - Clarify error handling path.

v2->v3:
 - Use correct map type.
====================

Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>