patch 8.0.0443: terminal width is set to 80 in test3

Problem:    Terminal width is set to 80 in test3.
Solution:   Instead of setting 'columns' set 'wrapmargin' depending on
            'columns.

Author: brammool

src/testdir/test3.in

@@ -970,7 +970,8 @@ break;
 /* end of AUTO */
 
 STARTTEST
-:set tw=0 wm=60 columns=80 noai fo=croq
+:set tw=0 noai fo=croq
+:let &wm = &columns - 20
 /serious/e
 a about life, the universe, and the rest
 ENDTEST

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    443,
 /**/
     442,
 /**/