perf bpf: Make synthesize_bpf_events() receive perf_session pointer instead of perf_tool

This patch changes the arguments of perf_event__synthesize_bpf_events()
to include perf_session* instead of perf_tool*. perf_session will be
used in the next patch.

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: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/20190312053051.2690567-6-songliubraving@fb.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>