hwc: Support for windowboxing feature on external

1. This feature is targeted to remove any window/pillar boxing on
   external display when zoom mode is enabled.
2. Preserve the aspect ratio of the external display by cropping and
   upscaling the tagged video layer during video playback on external.
3. User can tag the layers to be displayed on external display.
4. Set sys.hwc.windowbox_feature to true to enable this feature

Assumptions & Limitation:
    1. Tagged layers for external display will also be displayed on
       primary display along with untagged layers
    2. When zoom in mode is enabled, source crop left and source crop
       top of a tagged video layer is always assumed to be set to
       positive integer value. So pinch zoom feature or zooming in top
       left corner of the video use case cannot be supported.
    3. Except tagged video layers, all other tagged UI layers will
       use GPU for composition on external display, So all tagged UI
       layers cannot be secure layer.
    4. Rotation animation cannot be supported for this feature.

Change-Id: I8b934cf616ec23b4359d0120f9a291178a2781c6
4 files changed