perf tools: Make alias matching case-insensitive

Make alias matching the events parser case-insensitive. This is useful
with the JSON events. perf uses lower case events, but the CPU manuals
generally use upper case event names. The JSON files use lower case by
default too. But if we search case insensitively then users can
cut-n-paste the upper case event names.

So the following works:

% perf stat -e BR_INST_EXEC.TAKEN_INDIRECT_NEAR_CALL true

 Performance counter stats for 'true':

               305      BR_INST_EXEC.TAKEN_INDIRECT_NEAR_CALL

       0.000492799 seconds time elapsed
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
Tested-by: NArnaldo 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/1473978296-20712-17-git-send-email-sukadev@linux.vnet.ibm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.c

@@ -1459,7 +1459,7 @@ comp_pmu(const void *p1, const void *p2)
 	struct perf_pmu_event_symbol *pmu1 = (struct perf_pmu_event_symbol *) p1;
 	struct perf_pmu_event_symbol *pmu2 = (struct perf_pmu_event_symbol *) p2;
 
-	return strcmp(pmu1->symbol, pmu2->symbol);
+	return strcasecmp(pmu1->symbol, pmu2->symbol);
 }
 
 static void perf_pmu__parse_cleanup(void)