[Bug tree-optimization/119003] walk_aliased_vdefs and others are missing a comment in the front of it descriping what it does

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119003

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The comment is before the respective workers (walk_aliased_vdefs_1 for
example), copy-pasting leads to divergence so I tend to omit the duplication
...