Support using boot image on system when compiling system server.

When compiling system server, odrefresh assumes that boot classpath
artifacts are on data, which is not necessarily true now because we
don't re-compile boot classpath jars unless there is an ART update.

Bug: 197176583
Test: atest art_standalone_odrefresh_tests
Change-Id: I613e8ce8a97ff5ec6e8dcb6fc7975363220a021c
3 files changed