[Bug fortran/31016] Use __buildin_memcpy and __memcpy for array assignment

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31016

--- Comment #10 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Excellent news: The __builtin_memcpy cases have been fixed in the
meantime, and using __builtin_memset for values of more than one
byte doesn't work.

I will commit a test case and then close.