patch 9.0.0329: ":highlight" hangs when 'cmdheight' is zero

Problem:    ":highlight" hangs when 'cmdheight' is zero.
Solution:   Add to msg_col when using the message window. (closes #11014)
diff --git a/src/message.c b/src/message.c
index f92c454..0c8280e 100644
--- a/src/message.c
+++ b/src/message.c
@@ -2261,7 +2261,7 @@
 #ifdef HAS_MESSAGE_WINDOW
 
 /*
- * Put text "t_s" until "s" in the message window.
+ * Put text "t_s" until "end" in the message window.
  * "where" specifies where to put the text.
  */
     static void
@@ -2308,7 +2308,7 @@
     redraw_win_later(wp, UPD_NOT_VALID);
 
     // set msg_col so that a newline is written if needed
-    msg_col = (int)STRLEN(t_s);
+    msg_col += (int)(end - t_s);
 }
 #endif