Currently the transformation of a long counted loop to a loop nest with an inner int counted loop is performed in 2 steps:

1- recognize the counted loop shape and build the loop nest
2- transform the inner loop into a counted loop

I propose changing this to a 3 steps process:

1- recognize the counted loop shape (transform the loop into a LongCountedLoop)
2- build the loop nest
3- transform the inner loop into a counted loop

The benefits are:

- the logic is cleaner because step 1 and 2 are now separated
- simple optimizations (loop iv type, empty loop elimination, parallel iv) can be implemented for LongCountedLoop by refactoring existing code