e_policy: fix bug for uniconify window by wm

e_policy: fix bug for uniconify window by wm

There was a bug that the fully-obscured partial window run uniconify_window by wm
when the new alpha opaque window was launched.

Suppose that the window stack is as below.
[top] WinA (full size - 0,0,1920x1080) - WinB (partial - 1,1,1920x1280) [bottom]
If we launch new WinC which set an alpha opaque, window stack should be as below.
[top] WinC (full size, 32bit, alpha opaque) - WinA - WinB [bottom]
In this case, WinB must not change visibility and iconic state.

But, e changed WinB's iconic state to uniconic and sent a pre-unobscured event.
This was because we didn't clip the geometry of the window by e_zone's geometry.

So, we add code to clip the window's geometry by the zone's geometry.

Change-Id: Ie3de71ae4c6c1b35e15f5ca478b3c2cac94dd08a