Module#remove_method with untrusted will not throw a SecurityError.

Test Script:
{{{
class T
  def foo ; end
end

T.untrust
$SAFE = 4

T.class_eval{ remove_method :foo }
}}}

git-svn-id: http://svn.macosforge.org/repository/ruby/MacRuby/trunk@5149 23306eb0-4c56-4727-a40e-e92c0eb68959

vm_method.c

@@ -14,7 +14,7 @@ remove_method(VALUE klass, ID mid)
     if (klass == rb_cObject) {
 	rb_secure(4);
     }
-    if (rb_safe_level() >= 4 && !OBJ_TAINTED(klass)) {
+    if (rb_safe_level() >= 4 && !OBJ_UNTRUSTED(klass)) {
 	rb_raise(rb_eSecurityError, "Insecure: can't remove method");
     }
     if (OBJ_FROZEN(klass)) {