Revert "Use module-ref for make-base-operation"

This isn't working, with make-base-operation changing from part of a
macro to a procedure, I'm not sure how to maintain compatability. I
think just switching to guile-fibers-next everywhere is the approach
to take.

This reverts commit f41d1853ce.

knots/timeout.scm

@@ -119,9 +119,7 @@
 
 (define (make-wait-operation ready? schedule-when-ready port
                              port-ready-fd this-procedure)
-  ((module-ref (resolve-interface '(fibers operations))
-               'make-base-operation)
-   #f
+  (make-base-operation #f
                        (lambda _
                          (and (ready? port) values))
                        (lambda (flag sched resume)