Optimize building prerotation deqp targets Uses source_set to share the objects created for non rotated targets. As a bonus, dEQP itself is no longer built with ANGLE_DEQP_* defines. Bug: angleproject:4901 Change-Id: I2319116e478be39150fac32a85a43787c050c76f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2540829 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>