perf tools: Remove duplicate struct forward declarations

'struct evlist' has been declared at 10th line.

'struct comm' has been declared at 15th line.

Remove the duplicates

Signed-off-by: Wan Jiabing <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kajol Jain <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: [e-mail]
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/metricgroup.h

···
 
 struct evlist;
 struct evsel;
-struct evlist;
 struct option;
 struct rblist;
 struct pmu_events_map;

tools/perf/util/thread-stack.h

···
 struct ip_callchain;
 struct symbol;
 struct dso;
-struct comm;
 struct perf_sample;
 struct addr_location;
 struct call_path;