Fixed a few types in function signatures so that base and
derived classes signatures match.

Change-Id: Ide9b9c78ff05be785b512451a36c836f35bd1f3d
Reviewed-on: https://swiftshader-review.googlesource.com/5463Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>