vrend: Check for the EXT version of polygon_offset_clamp
Also check for GL_EXT_polygon_offset_clamp when deciding whether the corresponding virgl feature is supported. This enables D3D11 in guest Wine (and thus Steam/Proton), when running on GLES hosts that support this extension.
Signed-off-by: Alexandros Frantzis alexandros.frantzis@collabora.com Reviewed-by: Gurchetan Singh gurchetansingh@chromium.org
Edited by Alexandros Frantzis