patch 8.1.1602: popup window cannot overflow on the left or right

Problem:    Popup window cannot overflow on the left or right.
Solution:   Only set the "fixed" option when it is in the dict. Set w_leftcol
            to allow for the popup overflowing on the left and use it when
            applying the mask.

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1602,
 /**/
     1601,
 /**/