patch 8.2.0584: viminfo file uses obsolete function file_readable()

Problem:    Viminfo file uses obsolete function file_readable().
Solution:   Use filereadable(). (closes #5934)
diff --git a/src/version.c b/src/version.c
index c0c2e98..c8a1d55 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    584,
+/**/
     583,
 /**/
     582,