Process resize events

Use select to listen for both input events and X events.
Resize events are sent as ConfigureNotify events, which includes the
new size. This new size is stored in w_width & w_height, which are
already being used to scale the touch dots appropriately.

BUG=chromium-os:19918
TEST=Build install on a Chromebook.  No change in behavior.
     Build and install on Ubuntu.  Resizing window should resize touch dots.

Change-Id: I1c3e6cc510e7104f404c6f4ec6d8fa8e44317af9