clean up libgui Android.bp

Put the common build configs for buffer queue core functionalities
inside a default, and use it in libgui and libgui_bufferqueu_static.

Note that we can't make libgui link libgui_bufferqueu_static, since
libgui_bufferqueu_static will always have NO_BUFFERHUB defined, but
libgui sets it only for vendor builds.

bug: 128894663
Change-Id: I129a4863cfbae80db1dcd1ec63d5dd41dee6c2e4