perf test: Update mmap read functions for backward-ring-buffer test

Use the new perf_mmap__read_* interfaces for overwrite ringbuffer test.

Commiter notes:

Testing:

  [root@seventh ~]# perf test -v backward
  48: Read backward ring buffer                             :
  --- start ---
  test child forked, pid 8309
  Using CPUID GenuineIntel-6-9E
  mmap size 1052672B
  mmap size 8192B
  Finished reading overwrite ring buffer: rewind
  test child finished with 0
  ---- end ----
  Read backward ring buffer: Ok
  [root@seventh ~]#
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-10-git-send-email-kan.liang@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/backward-ring-buffer.c

@@ -31,10 +31,12 @@ static int count_samples(struct perf_evlist *evlist, int *sample_count,
 	int i;
 
 	for (i = 0; i < evlist->nr_mmaps; i++) {
+		struct perf_mmap *map = &evlist->overwrite_mmap[i];
 		union perf_event *event;
+		u64 start, end;
 
-		perf_mmap__read_catchup(&evlist->overwrite_mmap[i]);
-		while ((event = perf_mmap__read_backward(&evlist->overwrite_mmap[i])) != NULL) {
+		perf_mmap__read_init(map, true, &start, &end);
+		while ((event = perf_mmap__read_event(map, true, &start, end)) != NULL) {
 			const u32 type = event->header.type;
 
 			switch (type) {
@@ -49,6 +51,7 @@ static int count_samples(struct perf_evlist *evlist, int *sample_count,
 				return TEST_FAIL;
 			}
 		}
+		perf_mmap__read_done(map);
 	}
 	return TEST_OK;
 }