init was showing the :HG
modifier:

  $ perf stat usleep 1

   Performance counter stats for 'usleep 1':

            0.942119 task-clock                #    0.454 CPUs utilized
                   1 context-switches          #    0.001 M/sec
                   0 CPU-migrations            #    0.000 K/sec
                 126 page-faults               #    0.134 M/sec
             693,193 cycles:HG                 #    0.736 GHz                     [40.11%]
             407,461 stalled-cycles-frontend:HG #   58.78% frontend cycles idle    [72.29%]
             365,403 stalled-cycles-backend:HG #   52.71% backend  cycles idle
             465,982 instructions:HG           #    0.67  insns per cycle
                                               #    0.87  stalled cycles per insn
              89,760 branches:HG               #   95.275 M/sec
               6,178 branch-misses:HG          #    6.88% of all branches

         0.002077228 seconds time elapsed

While if one explicitely specifies the same events, which will make the parsing code
to be called and thus event_attr_init is called:

  $ perf stat -e task-clock,context-switches,migrations,page-faults,cycles,stalled-cycles-frontend,stalled-cycles-backend,instructions,branches,branch-misses usleep 1

   Performance counter stats for 'usleep 1':

            1.040349 task-clock                #    0.500 CPUs utilized
                   2 context-switches          #    0.002 M/sec
                   0 CPU-migrations            #    0.000 K/sec
                 127 page-faults               #    0.122 M/sec
             587,966 cycles                    #    0.565 GHz                     [13.18%]
             459,167 stalled-cycles-frontend   #   78.09% frontend cycles idle
             390,249 stalled-cycles-backend    #   66.37% backend  cycles idle
             504,006 instructions              #    0.86  insns per cycle
                                               #    0.91  stalled cycles per insn
              96,455 branches                  #   92.714 M/sec
               6,522 branch-misses             #    6.76% of all branches         [96.12%]

         0.002078681 seconds time elapsed

Fix it by introducing a perf_evlist__add_default_attrs method that will call
evlist_attr_init in all the perf_event_attr entries before adding the events.

Reported-by: Ingo Molnar <mingo@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-4eysr236r0pgiyum9epwxw7s@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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