Fix bug in X event processing.

An SkOSWindow for Unix may experience stuttering, with missed events or long delays before events are processed when using SkEvent.postDelay().

The issue is with the use of a select loop to watch for events coming into the x11 file descriptor for the display. It turns out there may be XEvents queued in memory but not yet processed that need to be handled before entering the select loop. See: http://developerweb.net/viewtopic.php?id=3184

BUG=1960
Committed: http://code.google.com/p/skia/source/detail?r=12874

[reed1, 2014-01-02 21:52:38]

the bots don't exercise this stuff. lgtm assuming you've build and run (and
interacted with) the linux SampleApp

[jcgregorio, 2014-01-02 22:01:04]

On 2014/01/02 21:52:38, reed1 wrote:
> the bots don't exercise this stuff. lgtm assuming you've build and run (and
> interacted with) the linux SampleApp

Yes, tested the SampleApp.

[commit-bot: I haz the power, 2014-01-02 22:01:12]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/jcgregorio@google.com/123303004/1

[commit-bot: I haz the power, 2014-01-02 22:21:49]

Change committed as 12874