SF: Support xy scaling for rounded corners

Currently only a single corner radius can be applied on a
layer. If the layer's x and y scale do not match, the average
is used to scale the corner radius. This can cause visual
defects in the rendered rounded corners.

This defect can be seen when moving the Camera app
to recents. The camera buffer is submitted with a rotation
and the layer's x and y scales are used to stretch the buffer
to the desired size in portrait mode.

Bug: 145094543
Test: atest librenderengine_test
Test: adb shell wm size 1000x1900 & animate camera app to recents
Change-Id: Ie76581eb200a57b847f619f4da0e61758f70dce7