perf evlist: Do not pass struct record_opts to perf_evlist__prepare_workload()

Since it's only used for checking ->pipe_output, we can pass the result
directly.

Now the perf_evlist__prepare_workload() don't have a dependency of
struct perf_record_opts, it can be called from other places like perf
stat.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1362987798-24969-5-git-send-email-namhyung@kernel.org


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