minigbm: remove vgem from minigbm (take 2)

minigbm: remove vgem from minigbm (take 2)

In theory, vgem is only used on Android, and nothing
should fail. In theory.  Otherwise, we can just revert
again.

BUG=b:141278896
TEST=compile

Change-Id: I998cb83d5342e454b876f4b74274df96b4951882
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/2412903
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Commit-Queue: Gurchetan Singh <gurchetansingh@chromium.org>