ART: Do not allow RETURN_VOID_NO_BARRIER outside constructors

Let the verifier fail non-constructor methods using the no-barrier
variant of return. This is a quickened return purely to avoid the
constructor barrier for final fields, and cannot be used as a stand-in
for a regular return.

Bug: https://code.google.com/p/android/issues/detail?id=181700
Bug: 22871329
Change-Id: I9559c6a1599c20ce526582527ebed73b25242767