Revert "Remove opaque check in GLRenderer when preparing dirty region."

 * This causes artifacts even with 8974 drivers.

This reverts commit c422280a7668ddbe1c4e399b083ec3d8a04059b1.

Change-Id: Iec4addc2d8aaeb6ce6a359aafd9fd9b97aef95e6
Merge remote branch 'cm/cm-10.1' into cm-10.1