Fix lockscreen selection view in landscape mode.

Added a dimen-value for selector in landscape-layout to fit screen. Issue is described here:
https://github.com/LegacyXperia/local_manifests/issues/677

Change-Id: I9501c91fed2660e947f1eae617f9a31d95766ed8
frameworks/base: Fix to avoid UI freeze issue.

Due to some race condition in WindowManagerService, Screenshot
layer remains as topmost and buffers are not flipped hence
no updates seen on the screen. So, trying to destroy persistent
layer explicitly if freeze timeout expires 6sec.

Change-Id: Ibe295550a7431a4f633a57e7dfab0cbda102ab87