patch 9.0.0662: concealed characters do not work correctly

Problem:    Concealed characters do not work correctly.
Solution:   Subtract boguscols instead of adding them. (closes #11273)
diff --git a/src/version.c b/src/version.c
index e9cc0ec..540ea37 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    662,
+/**/
     661,
 /**/
     660,