dex2oat: handle the case when a dm file and a vdex file are passed.

Package manager can pass both when an app moves location (for example,
it moves to a sdcard).

In this situation, just arbitrarily take the vdex file.

Test: test.py
Bug: 210081649
Bug: 210431530
(cherry picked from commit 8409281470fc4742a1ce2e7bac1638c37e874563)

Merged-In: I5ff972ae6ad86efa60f9ae25dae0ab9202ab9ff0
Change-Id: If52d3311f3da7872b4d6bb4e7e6a9738c337c3f3