goldfish-opengl: differentiate goldfish/virtio-gpu via minigbm only

Whether or not ANGLE is used isn't import for determining the
presence of the goldfish device.

BUG=213488545
TEST=boot VM, run apps

Cherry-picked from
https://android-review.git.corp.google.com/c/device/generic/goldfish-opengl/+/1948114
from HWC2 to HWC3.

git fetch https://android.googlesource.com/device/generic/goldfish-opengl refs/changes/14/1948114/1 && git format-patch -1 FETCH_HEAD --stdout |  git am -3 -p2 --directory='system/hwc3'

Change-Id: I88185c2591850e81e9f96d943df3ccb05162a9a9