ART: Hook Runtime APEX checker into build

Another attempt. Use automatic bitness detection and accept possible
imprecision/false-negatives. Disable for the Mac build.

Test: m com.android.runtime
Test: m art-check-release-apex-gen-fakebin
Test: m art-check-debug-apex-gen-fakebin
Change-Id: I8ffc38d8402025e0bc699f084d4c887e7a2507fd