test/tools/javac/enum/EnumImplicitPrivateConstructor.java failure

The regression test
test/tools/javac/enum/EnumImplicitPrivateConstructor.java assumes that
it can call java.lang.reflect.AccessibleObject.setAccessible.
However, one possible result of that call is an
AccessControlException, which is what is occurring when I run this
test. I think the test should be modified to consider that a correct
result, rather than a test failure.