Use HWC_NUM_DISPLY_TYPES for 1.3 as number of displays

Some Android hwcomposer implementations expect all displays being initialized even if not
used.

Signed-off-by: Simon Busch <morphis@gravedo.de>
Add support for changes in API version 1.3

Signed-off-by: Simon Busch <morphis@gravedo.de>
Require Android 4.3 for planeAlpha attribute

The addition of the planeAlpha attribute is one of the bad stories about the HAL
compatbility between different Android versions. It was added after 1.2 with jelly bean
but not marked as part of 1.2. It doesn't break the ABI. We're adding support for it
now depending on the Android version (>= 4.3).

Signed-off-by: Simon Busch <morphis@gravedo.de>
Merge pull request #21 from webOS-ports/hwcomposer-1.3-support

Hwcomposer 1.3 support