Currently we don't restrict any of the parameters (x, y, width, height)
to glScissor aside from forcing width and height to be non-negative.
This means large parameters can cause overflows during the scissor test.

So we change width/height in the cases where an overflow will happen.

Bug chromium:969071

Change-Id: Icb6992551aed6e3e086f96d89931eae0e99899a4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/32608
Presubmit-Ready: Sean Risser <srisser@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Sean Risser <srisser@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>