patch 9.0.0284: using static buffer for multiple completion functions

Problem:    Using static buffer for multiple completion functions.
Solution:   Use one buffer in expand_T.
diff --git a/src/version.c b/src/version.c
index c3fbe5f..2e48687 100644
--- a/src/version.c
+++ b/src/version.c
@@ -708,6 +708,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    284,
+/**/
     283,
 /**/
     282,