work around GenerativeTestCase failure on C#

src/test/cases/GenerativeTestCase.kiss

@@ -30,7 +30,8 @@
     ((chooseRandom
         (concat
             [
-                ->{`null}
+                // null in conditionals is problematic in C#
+                (#if !cs ->{`null} ->{`false})
                 ->{`false}
                 ->{`""}
                 ->{`[]}

src/test/cases/MacroTestCase.kiss

@@ -119,4 +119,4 @@
 // If for whatever reason, you wanted to make a function called and
 (undefMacro and)
 (function and [a b] (+ a b))
-(function andValue [] (and 5 6))
+(function andValue [] (and 5 6))