patch 9.0.1602: stray character visible if marker on top of double-wide char

Problem:    Stray character is visible if 'smoothscroll' marker is displayed
            on top of a double-wide character.
Solution:   When overwriting a double-width character with the 'smoothscroll'
            marker clear the second half. (closes #12469)
diff --git a/src/version.c b/src/version.c
index e373686..a724b7c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1602,
+/**/
     1601,
 /**/
     1600,