correct some tests in light of lazy "for"

integration/99problems-11-to-20.t

@@ -205,15 +205,15 @@ plan 25;
         'We should be able to drop list elements using gather';
 
     sub drop4(@list, Int $nth) {
-        return (@list[$_] if ($_+1) % $nth) for ^@list;
+        (@list[$_] if ($_+1) % $nth) for ^@list;
     }
     #?rakudo todo 'unknown'
     #?niecza todo
     is drop4(<a b c d e f g h i k>, 3), <a b d e g h k>,
         'We should be able to drop list elements using (statement if) for';
 
     sub drop5(@list, Int $nth) {
-        return @list[$_] if ($_+1) % $nth for ^@list;
+        @list[$_] if ($_+1) % $nth for ^@list;
     }
     #?rakudo todo 'unknown'
     #?niecza todo

integration/99problems-31-to-40.t

@@ -264,6 +264,7 @@ plan 67;
                 return ($x,$y) if $x+$y == $n;
             }
         }
+        0;
     }
 
     is goldbach(28), (5, 23), "Goldbach works.";

integration/99problems-41-to-50.t

@@ -44,6 +44,7 @@ plan 11;
                 return ($x,$y) if $x+$y == $n;
             }
         }
+        0;
     }
 
     sub goldbachs($from, $to) {