Stop using DIST_DIR directly, use dist-for-goals

We're moving DIST_DIR handling outside of the Kati instance that reads
these makefiles. As such, the dist file actually needs to be represented
in the build graph, not as a side effect of a phony rule. All of the
dependencies of that phony rule must be actual files in that graph now
too, not other phony rules.

Bug: 117463001
Test: DIST_DIR=dist ./art/test/testrunner/run_build_test_target.py -j50 art-gtest
Change-Id: I15d5a2c28321ff7f0f8d7d99dc697bd0393380cb