perf evlist: Open event on evsel cpus and threads

An evsel may have different cpus and threads than the evlist it is in.

Use it's own cpus and threads, when opening the evsel in 'perf record'.

Signed-off-by: Kan Liang <kan.liang@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1440138194-17001-1-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>