perf tools: Add unit_number__scnprintf function

Add unit_number__scnprintf function to display size units and use it in
-m option info message.

Before:
  $ perf record -m 10M ls
  rounding mmap pages size to 16777216 bytes (4096 pages)
  ...

After:
  $ perf record -m 10M ls
  rounding mmap pages size to 16M (4096 pages)
  ...

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1483955520-29063-2-git-send-email-jolsa@kernel.org
[ Rename it to unit_number__scnprintf for consistency ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 1d639e3..6e8be17 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -363,4 +363,5 @@ int is_printable_array(char *p, unsigned int len);
 
 int timestamp__scnprintf_usec(u64 timestamp, char *buf, size_t sz);
 
+int unit_number__scnprintf(char *buf, size_t size, u64 n);
 #endif /* GIT_COMPAT_UTIL_H */