This allows us to preserve the various product definitions during the compile
phase, and allows us to select the product in the link phase.
This allows compiled files to remain product-independent, so that they do not need
to be recompiled when switching targets.
Bug:25958912
Change-Id: Iaa7eed25c834b67a39cdc9be43613e8b5ab6cdd7
e4bb9eb5af