Update make rules to use new android.jar location.

This file has been copied into a 'public' subdir. Use that, so that
the old file can be deleted. Also introduce a new macro to avoid
duplicating this path in a bunch of places.

Bug: 77525052
Test: m checkbuild
Change-Id: Ifcf59c6fb357769b2765e417c8dd56d2ad9b97aa