[11u] RFR (S) 8238175: CTW: Class.getDeclaredMethods fails with assert(k->is_subclass_of(SystemDictionary::Throwable_klass())) failed: invalid exception class

[Aleksey Shipilev]

Original bug:
   https://bugs.openjdk.java.net/browse/JDK-8238175
   https://hg.openjdk.java.net/jdk/jdk/rev/b7f4baa47fe2

This should improve cleanliness for CTW runs: the patch relaxes the assert to warning.

Unfortunately, the test does not run on 11u, because .jcod sets too high class version. I reduced 
the class version to the one JDK 11 accepts. There are no other changes.

11u webrev:
   https://cr.openjdk.java.net/~shade/8238175/webrev.11u.01/

Testing: new regression test (fails before, passes now); tier{1,2}

-- 
Thanks,
-Aleksey