[Bug tree-optimization/125567] SLP build misses operand swapping for a commutative scalar-vector add pattern

[chenzhongyao.hit at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125567

--- Comment #8 from Zhongyao Chen <chenzhongyao.hit at gmail dot com> ---
Yes, boolean is good, I prefer it too. and it works in this case.

To be honest, the reason I used a depth counter was that I got a bit dizzy
during debugging recursive calls. and it just simply got left.