perf list jevents: Add support for event list topics

Add support to group the output of perf list by the Topic field in the
JSON file.

Example output:

% perf list
...
Cache:
  l1d.replacement
       [L1D data line replacements]
  l1d_pend_miss.pending
       [L1D miss oustandings duration in cycles]
  l1d_pend_miss.pending_cycles
       [Cycles with L1D load Misses outstanding]
  l2_l1d_wb_rqsts.all
       [Not rejected writebacks from L1D to L2 cache lines in any state]
  l2_l1d_wb_rqsts.hit_e
       [Not rejected writebacks from L1D to L2 cache lines in E state]
  l2_l1d_wb_rqsts.hit_m
       [Not rejected writebacks from L1D to L2 cache lines in M state]

...
Pipeline:
  arith.fpu_div
       [Divide operations executed]
  arith.fpu_div_active
       [Cycles when divider is busy executing divide operations]
  baclears.any
       [Counts the total number when the front end is resteered, mainly
       when the BPU cannot provide a correct prediction and this is
       corrected by other branch handling mechanisms at the front end]
  br_inst_exec.all_branches
       [Speculative and retired branches]
  br_inst_exec.all_conditional
       [Speculative and retired macro-conditional branches]
  br_inst_exec.all_direct_jmp
       [Speculative and retired macro-unconditional branches excluding
       calls and indirects]
  br_inst_exec.all_direct_near_call
       [Speculative and retired direct near calls]
  br_inst_exec.all_indirect_jump_non_call_ret

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1473978296-20712-14-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>