Indicate ANGLE is present on devices

The system property ro.gfx.angle.supported needs to be enabled when
ANGLE is included in a build to indicate to the platform and CTS tests
that ANGLE is present on the device.

Test: atest CtsAngleIntegrationHostTestCases
Bug: 157670307
Merged-in: Ide4e3d8f78d3748d557a47ecd153d66694fd1e3a
Change-Id: I72ba8731fed36dbc594dae88aaa00a6299e8f4ae