src:android-platform-build also has build-profiles, which eliminates the circular dependency. Beyond Nougat, this circular dependency would be removed since android-platform-build-headers are no longer needed.
Out of topic here: Build-profiles are pretty good ways to deal with bootstrapping issues! However I would like to see the support of build-profiles in Buildd, since manually removing <!stage1> entries in d/control and preparing a "~stage1" version isn't very elegant, as we have been doing in the Nougat updates. See <https://packages.debian.org/source/experimental/android-platform-system-core>.