perf list: Support matching by topic

Add support in perf list topic to only show events belonging to a
specific vendor events topic. For example the following works now:

% perf list frontend
List of pre-defined events (to be used in -e):

stalled-cycles-frontend OR idle-cycles-frontend [Hardware event]

stalled-cycles-frontend OR cpu/stalled-cycles-frontend/ [Kernel PMU event]

frontend:
dsb2mite_switches.count
[Decode Stream Buffer (DSB)-to-MITE switches]
dsb2mite_switches.penalty_cycles
[Decode Stream Buffer (DSB)-to-MITE switch true penalty cycles]
dsb_fill.exceed_dsb_lines
[Cycles when Decode Stream Buffer (DSB) fill encounter more than 3 Decode Stream Buffer (DSB)
lines]
icache.hit
[Number of Instruction Cache, Streaming Buffer and Victim Cache Reads. both cacheable and
noncacheable, including UC fetches]
...

Signed-off-by: Andi Kleen <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/pmu.c

···
 			if (event_glob != NULL &&
 			    !(strglobmatch_nocase(name, event_glob) ||
 			      (!is_cpu && strglobmatch_nocase(alias->name,
-						       event_glob))))
+						       event_glob)) ||
+			      (alias->topic &&
+			       strglobmatch_nocase(alias->topic, event_glob))))
 				continue;
 
 			if (is_cpu && !name_only && !alias->desc)