Make dex file loading failure more explicit about failure.

We make sure that if we fail to load a dex file due to having an
unsupported dex version number we will say so explicitly in the
exceptions.

Bug: 28269864
Change-Id: Ib9bf6eca941f5bfc2a0bbc511d7a76e0fb3fd4bf
(cherry picked from commit 8b0358ee)