Merge branch 'bpf-verifier-resilience'

Alexei Starovoitov says:

====================
Three patches to improve verifier ability to handle pathological bpf
programs with a lot of branches:

- make sure prog_load syscall can be aborted
- improve branch taken analysis
- introduce per-insn complexity limit for unprivileged programs
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>