SystemUI: fix wrong statusbar background.

If we turned off screen while some panel was visible than
background of PhoneStatusBarView will not be updated because we receiving single
panelExpansionChanged call and after super.panelExpansionChanged mFadingPanel
will be null (onAllPanelsCollapsed cause this).

Allow updating background when mFadingPanel is null.

Change-Id: Ib123f27500790c1b7ec787b7e433372629daa08d
bootanim: Don't cache textures if they're expected to use a lot of VRAM

bootanimation cached all the textures generated until the animation
was completed.
For Hi-res animations with lots of frames (like the new CM9 anim on
xhdpi devices), this implied using large amounts of video RAM, more
than most devices actually have available, causing the animation to
stall (and in some cases, gralloc to lock up); so if an animation is
expected to use a lot of RAM (rough estimation based on frame size
and number of frames), disable cache entirely and generate the textures
on demand

Change-Id: I65b6358d8ddda4350e1f150034c340b22aba5f27
bootanimation: performance enhancements

This patch implements two simple performance enhancements, which
might benefit devices. They are completely opt-in by setting
the following variables.

  * TARGET_BOOTANIMATION_PRELOAD: will preload the bootanimation
    zip to memory; this is handy on devices where the storage
    might be slow. By preloading it, we get quick access to the
    zip file, and the animation doesn't stutter.

  * TARGET_BOOTANIMATION_TEXTURE_CACHE: allows maintainers to
    force texture cache on/off.

Also fixes the sign warnings related to int / size_t comparison

Change-Id: Ibfd04caf019bcac9ba9f80f8c3eadca397a998d1