Always unlink the out_vdex_file.

Even if we pass the same vdex file as input and output to
dex2oat, make sure we unlink it if dex2oat failed.

bug:38113240
Test: manual, killing dex2oat invocation

(cherry picked from commit 7bb16577)

Change-Id: I157b3d33179b5bff1ca38750bee24aab01c5a19b