perf test: Add 'struct test *' to the test functions

This way we'll be able to pass more test specific parameters without
having to change this function signature.

Will be used by the upcoming 'shell tests', shell scripts that will
call perf tools and check if they work as expected, comparing its
effects on the system (think 'perf probe foo') the output produced, etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-wq250w7j1opbzyiynozuajbl@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/unit_number__scnprintf.c

@@ -5,7 +5,7 @@
 #include "units.h"
 #include "debug.h"
 
-int test__unit_number__scnprint(int subtest __maybe_unused)
+int test__unit_number__scnprint(struct test *t __maybe_unused, int subtest __maybe_unused)
 {
 	struct {
 		u64		 n;