drm_hwcomposer: implement Gralloc 4 BufferInfoMapperMetadata

Implements the BufferInfoMapperMetadata that uses the
GraphicBufferMapper to set the fields of the hwc_drm_bo_t struct.

New class function GetFds created to obtain the file descriptors from
the native_handle_t. Function is marked weak so that vendors can
override it to match their system if required.

Change-Id: I74445487dec6bda2915b21f4b63804832bfead23
Signed-off-by: Dennis Tsiang <dennis.tsiang@arm.com>
Reviewed-by: Roman Stratiienko <r.stratiienko@gmail.com>
1 job for bufferinfomappermetadata in 33 seconds (queued for 1 second)