Fixes ReactorUnitTests.FRem failing on Windows x86.

Bug: b/173800469
Change-Id: I199d28f9ca532870b92a7da38d42c1cf652829a5
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/50708
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>