ANDROID: virglrenderer: stub out virgl gbm winsys am: 94efc9096b

Original change: https://android-review.googlesource.com/c/platform/external/virglrenderer/+/3145758

Change-Id: I21bb07774b9e303acd1d4b2c6f02ddc393fd2b0d
Signed-off-by: Automerger Merge Worker <[email protected]>