add main target logic to glue Gentoo packages in

This is the main entry point for gluing Gentoo packages in.
To use this, just update your device's mk files like so:
PRODUCT_3RD_PARTY_PACKAGES := <list of Gentoo packages>
PRODUCT_PACKAGES += 3rd-party-packages

When you build, those packages will be built & installed automatically.

Examples for building your own code against those will be a follow up

TEST=built packages and they worked in qemu

Change-Id: Ic86d62415fdab1b94947dbfa7658264c2824d6e0
2 files changed
tree: 0ee74de8258f62086219d477a0ece835dccb7d9b
  2. TODO
  3. portage/
  4. toolchain/