MFB: There won't be a warning/fix on this, so remove the test

tests/lang/bug20993.phpt

@@ -1,31 +0,0 @@
---TEST--
-Bug #20993 (referenced array key, makes array global)
---SKIPIF--
-<?php
-if(TRUE)
-	die("skip fix for this problem is yet undecided.");
-?>
---FILE--
-<?php
-$a = array(1);
-$b = array(1);
-$ref =& $a[0];
-
-echo $a[0], ' -b ', $b[0], ' -r ', $ref,  "\n";
-changeVal($a);
-echo $a[0], ' -b ', $b[0], ' -r ', $ref,  "\n";
-changeVal($b);
-echo $a[0], ' -b ', $b[0], ' -r ', $ref,  "\n";
-
-function changeVal($arr)
-{
-	$arr[0] = 2;
-}
-?>
---EXPECTF--
-1 -b 1 -r 1
-
-Notice: %s referenced element(s) %s
-%s
-2 -b 1 -r 2
-2 -b 1 -r 2