perf tools: Force period term to overload global settings

Currently the command line option settings beats the per event period
settings:

With no global settings, we get per-event configuration:

  $ perf record -e 'cpu/instructions,period=20000/' sleep 1
  $ perf evlist -v
  ... { sample_period, sample_freq }: 20000 ...

With 'c' option period setup, we get 'c' option value:
  $ perf record -e 'cpu/instructions,period=20000/' -c 1000 sleep 1
  $ perf evlist -v
  ... { sample_period, sample_freq }: 1000 ...

This patch makes the per-event settings overload the global 'c' option
setup:

  $ perf record -e 'cpu/instructions,period=20000/' -c 1000 sleep 1
  $ perf evlist -v
  ... { sample_period, sample_freq }: 20000 ...

I think the making the per-event settings to overload any other config
makes more sense than current state. However it breaks the current
'period' term handling, which might cause some noise.. so let's see ;-).

Also fixing parse event tests with the new behaviour.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1438162936-59698-3-git-send-email-kan.liang@intel.com
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evsel.h

@@ -38,6 +38,7 @@ struct cgroup_sel;
  * perf_evsel::config_terms list head.
 */
 enum {
+	PERF_EVSEL__CONFIG_TERM_PERIOD,
 	PERF_EVSEL__CONFIG_TERM_MAX,
 };