[Bug tree-optimization/96669] Failure to optimize shift by variable+and by 1 to test for 0

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96669

--- Comment #1 from Gabriel Ravier <gabravier at gmail dot com> ---
PS: This can also be done when the shift is a right shift instead of a left
shift (i.e. `1 >> x` is used instead of `1 << x`)