Hi Wookey, Thanks for your bug report!
I have spotted the issue and fixed it in VCS. Please see: <https://anonscm.debian.org/cgit/android-tools/android-platform-system-core.git/commit/?id=6a17508>. libunwind and safe-iop are indeed needed in stage1, as well as pandoc (I guess you had typos?). We never intended to set a stage for "nodoc" which, so I also included it in stage1. However I'm not sure about your point of self dependency of andoid-platform-system-core-headers. This package does not build-depend on it, but instead depends on android-platform-build-headers.
