st-api: Rework how drawables are invalidated v3.

st-api: Rework how drawables are invalidated v3.

The api and the state tracker manager code as well as the state tracker code
assumed that only a single context could be bound to a drawable. That is not
a valid assumption, since multiple contexts can bind to the same drawable.

Fix this by making it the state tracker's responsibility to update all
contexts binding to a drawable

Note that the state trackers themselves don't use atomic stamps on
frame-buffers. Multiple context rendering to the same drawable should
be protected by the application.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>