Do not crash on out-of-date oat files.

Check that the OatHeader is valid before searching
the key-value store for "debuggable".

(cherry picked from commit ef8c3376a812e943d4e7c4ef96f17e218d11bc7c)

Test: New test in dex2oat_test.cc .
Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 179221298
Change-Id: I77585ae3e78d19117e31a6ad0ebee6e32bff8730
Merged-In: Ib10c919883b31b71810cc876fb38105b48a58bcb
3 files changed