perf/tool: Add automated test for pure terms parsing

Adding automated test for parsing terms out of the event grammar.
Also slightly changing current event parsing test functions to
follow up more generic namespace.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1339741902-8449-14-git-send-email-zheng.z.yan@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>