Currently, monitoring of BPF programs through bpf_event is off by
default for 'perf record'.

To turn it on, the user need to use option "--bpf-event".  As BPF gets
wider adoption in different subsystems, this option becomes
inconvenient.

This patch makes bpf_event on by default, and adds option "--no-bpf-event"
to turn it off. Since option --bpf-event is not released yet, it is safe
to remove it.
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: kernel-team@fb.com
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislav Fomichev <sdf@google.com>
Link: http://lkml.kernel.org/r/20190312053051.2690567-2-songliubraving@fb.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>