Allow GetSystemInfo to return false in CGL and EAGL backends. This API is documented as returning false if information is incomplete, but this should not cause a failure to initialize ANGLE's Display. This change is a refinement of one made in WebKit's downstream copy of ANGLE, likely in support of forthcoming Macs with Apple Silicon, in https://bugs.webkit.org/show_bug.cgi?id=213479 . Bug: angleproject:4902 Change-Id: I40a664a5db67b2aa37f15617b1cbcc3119793ee0 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2324462 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com> Commit-Queue: Kenneth Russell <kbr@chromium.org>