Add hidden negative button constants

The support library was recently merged in frameworks/support, and exposes
the negative button action through an onError message (instead of an
OnClickListener). These change adds a placeholder in frameworks/base
so that the constants are kept in sync.

Fixes: 77969138

Test: builds
Change-Id: Ic1d142006c09e1d4b9149540554e4f068e666798