Make foldr2 a bit more strict

in order to make its RULES semantics preserving. This fixes #9495.
Make scanr a good producer and consumer

This fixes #9355.
Make mapAccumL a good consumer

This fixes #9502.
Fusion rule for "foldr k z (x:build g)"

There seem to be various issues with general fold/cons and even
cons/build rules, but it seems pretty clear to me that the simple
fold/cons/build rule is a good idea. It doesn't do much for nofib
allocation, but it seems to improve some other analyses and speed
several benchmarks up. Implements #9536.
Make filterM a good consumer

analogously to mapM. Fixes #9546.
Simplify mergeSATInfo by using zipWith

Closes #9561.