PR 66280 -- ICE in tree-optimizer

[Salvatore Filippone]

Folks,
I have hit an ICE in tree-optimizer that was supposed to be already
fixed on trunk by a patch, committed  at r223927, but it still
surfaces for me at  r224364.

I have added a new test case to the PR.
The original test case is in C++; now, this is an optimizer bug, but
maybe there is something in the Fortran front-end that needs
adjusting?
I thought a heads-up would do no harm....
Salvatore