All current texture environment parameters are integer, so just pass them
through to glTexEnvi().

Change-Id: I2f1abea0d6da0e76b7ef305588ffc65fead32502
Reviewed-on: https://swiftshader-review.googlesource.com/2701Reviewed-by: Greg Hartman <ghartman@google.com>
Tested-by: Greg Hartman <ghartman@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>