ART: Refactor `RelocateAppImage()` arguments...

... and do not return any value. This aligns with the
`RelocateBootImage()` in preparation for unifying the
two functions.

Test: testrunner.py -b --host-gtest --host --relocate \
      --optimizing --speed-profile
Flag: EXEMPT PURE_REFACTOR
Change-Id: I79f988ac01ecee2007055d40ee0a4d6372332e5d