The reply function for xcb_get_geometry was called without handling errors,
causing a null-dereference in the fuzzer. These calls should be wrapped and
handled safely.

Bug: chromium:1080987
Change-Id: Ie1377909b68375fa9bc6eb54bdcbfda0627fd680
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/45068
Presubmit-Ready: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Jonah Ryan-Davis <jonahr@google.com>