libperf tests: Fix verbose printing

libperf's verbose printing checks the -v option every time the macro _T_ START
is called.

Since there are currently four libperf tests registered, the macro _T_ START is
called four times, but verbose printing after the second time is not output.

Resets the index of the element processed by getopt() and fix verbose printing
so that it prints in all tests.

Signed-off-by: Shunsuke Nakamura <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/perf/include/internal/tests.h

···
 			break;
 		}
 	}
+	optind = 1;
+
 	return verbose;
 }