Remove Pointer Capture API

The underlying implementation needs to be completely rethought. If a
process crashed while you were in pointer capture mode, you were
pretty much stuck in it. If the mouse happened to move outside of
your bounds right before you called the API, you'd never actually get
an event (whatever it was hovering over would). There's no easy way
for the system to tell you when you enter or exit this mode because
it doesn't actually track who the current request is from.

These are all solvable, but not in the N time frame. Maybe next time.

Bug: 26830970
Change-Id: I899649594c7ca8db5962fcdaa71c5b21d3aa42c3