drm_hwcomposer: Create make target to test filegroups

Android.bp contains filegroups that are not built by default
(e.g. using $ mmma external/drm_hwcomposer)

Fix it.

To ensure build will work on wide range of Android versions,
pull depended headers from AOSP-11 tree:
1. Mali: "device/linaro/hikey/gralloc960"
2. Imagination: "hardware/ti/am57x/libhwcomposer"
and put it into ./tests/test_include directory.