Build everything in PRODUCT_HOST_PACKAGES

This should only add extra host packages that were in
PRODUCT_HOST_PACKAGES and not PRODUCT_PACKAGES.

That shouldn't be very many things -- user builds will build a few more
host tools that used to be in PRODUCT_PACKAGES_DEBUG, etc.

Test: treehugger
Change-Id: I6768b76db74ea049de90eef326d1e314eb4ef848