[Bug tree-optimization/93556] lower mempcpy to memcpy when result is unused

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93556

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
One more thing BUILT_IN_MEMPCPY gets changed into BUILT_IN_MEMCPY like
BUILT_IN_STPCPY is being changed into BUILT_IN_STRCPY in
gimple_fold_builtin_stpcpy.