[Bug target/81356] __builtin_strcpy is not good for copying an empty string on aarch64

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81356

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
A GIMPLE level optimization to *a = '\0'; would still be ok but I agree with
Andrew.