Clarify the format and assumptions on the dex file locations.

libnativeloader now uses them more often to determine how to load
libraries based on the java caller location, and then it relies on them
being absolute paths.

Test: n/a - comment change only
Bug: 237577392
Change-Id: I6700c0182e3c942a76880307c5947bfca4c1d0d9
2 files changed