[Bug sanitizer/70717] -fsanitize=object-size as warning

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70717

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
-D_FORTIFY_SOURCE=1 or -D_FORTIFY_SOURCE=2 handle this well:
warning: call to __builtin___memcpy_chk will always overflow destination buffer