[Bug tree-optimization/96963] -Wstringop-overflow false positive on -O3 or -O2 -ftree-vectorize when assigning consecutive char struct members

[gcc_bugzilla at venus dot thegavinli.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96963

--- Comment #3 from Gavin <gcc_bugzilla at venus dot thegavinli.com> ---
Correct. Due to store-merging, -O2 and -O3 generate the same machine code on
both x86_64 and armv7m.