bpf: implement decoding of BPF_MAP_LOOKUP_AND_DELETE_ELEM command

bpf: implement decoding of BPF_MAP_LOOKUP_AND_DELETE_ELEM command

BPF_MAP_LOOKUP_AND_DELETE_ELEM command was introduced by Linux commit
v4.20-rc1~151^2~32^2~11^2~2.

* bpf.c (decode_BPF_MAP_LOOKUP_AND_DELETE_ELEM): Alias
to decode_BPF_MAP_LOOKUP_ELEM.
(SYS_FUNC(bpf)) <bpf_cmd_decoders[]>: Add
BPF_CMD_ENTRY(BPF_MAP_LOOKUP_AND_DELETE_ELEM).
* tests/bpf.c (BPF_MAP_LOOKUP_AND_DELETE_ELEM_checks): Alias
to BPF_MAP_LOOKUP_ELEM_checks.
(main) <checks>: Add CHK(BPF_MAP_LOOKUP_AND_DELETE_ELEM).