hwui: Don't discard framebuffer on exynos4

The layers gets empty/not cleaned and redrawn on top of the preview,
causing beautiful glitch on homescreen, and drawing black instead
of transparency.

Change-Id: I633b104224c73c625f1193ee3dde41823cddc5bf
Wimax: Squashed commit of the following:

Port WimaxHelper and (the toggle) WimaxButton from CM7.

Both WimaxHelper and WimaxButton are updated to support Samsung's
(crespo4g, epicmtd) Wimax4GManager proprietary class, whose API has been
somewhat-significantly changed in ICS.  Support for HTC's (supersonic,
speedy) WimaxController is retained in WimaxHelper, although untested.

Note that WimaxManagerConstants was previously misdocumented, confabulating
the lookup key EXTRA_4G_STATE ("4g_state") with EXTRA_WIMAX_STATUS
("wimax_status"), which no longer exists.  This is also fixed.

SQN: WiMAX: add support for Sequans WiMAX devices

issue: 4G icon does not display when connected to wimax

Change-Id: If199c9251a7abd679b048b5aba3f601b4bf9047e