Null initialize dirty_image_objects_filename_

Fixes ASAN dex2oat.

Test: build boot image with ASAN dex2oat

(cherry picked from commit ff0baff1c54d193f2c4e9b2f9fd229a8fd9c7bdc)

Bug: 62554875

Change-Id: Ib581d29fca97dc609616e43552cf306b0cd084ea
1 file changed