The dynamic sort key requires event name but specifying full event name
is rather inconvenient.  This patch adds more ways to identify the event
in a more compact way.

  1. If session has just one event, event name can be omitted.
  2. Events can be accessed by index preceded by a percent sign.
  3. A part of the name can be used, if it's not ambiguous.  The partial
     name should not contain ':' in it.
  4. Full system + event name is still used, it should contain ':'.

So in the below example all does same thing:

  $ perf record -e sched:sched_switch -a sleep 1

  $ perf report -s next_pid,next_comm
  $ perf report -s %1.next_pid,%1.next_comm
  $ perf report -s switch.next_pid,switch.next_comm
  $ perf report -s sched:sched_switch.next_pid,sched:sched_switch.next_comm
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1450804030-29193-10-git-send-email-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>