patch 8.1.1213: "make clean" in top dir does not cleanup indent test output

Problem:    "make clean" in top dir does not cleanup indent test output.
Solution:   Clean the indent test output.  Do not rely on the vim executable
            for that. (closes #4307)
diff --git a/src/version.c b/src/version.c
index 704ff54..88763e5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -768,6 +768,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1213,
+/**/
     1212,
 /**/
     1211,