stat: fixup fio-dump-status file location

Don't use /tmp in the actual file name. And kill unused Windows
os_get_tmpdir().

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/stat.c b/stat.c
index e43db8f..f018f33 100644
--- a/stat.c
+++ b/stat.c
@@ -1480,7 +1480,7 @@
 static int status_interval_init;
 static struct timeval status_time;
 
-#define FIO_STATUS_FILE		"/tmp/fio-dump-status"
+#define FIO_STATUS_FILE		"fio-dump-status"
 
 static int check_status_file(void)
 {