patch 9.0.1506: line number not displayed when using 'smoothscroll'

Problem:    Line number not displayed when using 'smoothscroll'.
Solution:   Adjust condition for showing the line number. (closes #12333)
diff --git a/src/version.c b/src/version.c
index d01d7f2..b708254 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1506,
+/**/
     1505,
 /**/
     1504,