CP: Use empty region when buffer age is not supported

CP: Use empty region when buffer age is not supported

In the dEQP-EGL.functional.partial_update.* tests the damage region
needs to set to empty instead of implicit full screen for frame that do
not draw when the EGL_KHR_buffer_age is not supported. Otherwise the
contents become invalid and cannot be verified.

Bug: 30735352
Test: Local run of dEQP-EGL.functional.partial_update.* on various Nexus devices

(cherry picked from commit bc29554d7eed0bd996506fc1e074f264305c8143)

Change-Id: I17fc4fdca1da176e13e78b1ec2bebc8cb6d266b0