perf test: Use header file util/debug.h

Use the header file util/debug.h instead of declaration of verbose
variable.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180528134817.36643-1-tmricht@linux.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/python-use.c

@@ -7,8 +7,7 @@
 #include <stdlib.h>
 #include <linux/compiler.h>
 #include "tests.h"
-
-extern int verbose;
+#include "util/debug.h"
 
 int test__python_use(struct test *test __maybe_unused, int subtest __maybe_unused)
 {