Fix boot image size check.

Test: aosp_taimen-userdebug boots when built with
      export DEXPREOPT_USE_ART_IMAGE=true
      and logcat shows no messages about failing to open
      the app image services.art .
Bug: 150668267
Change-Id: I800ef2e09e3a61fe4c8418ba4d66f54dd605495e
1 file changed