[Bug fortran/65921] GFortran should use __builtin_mul_overflow when checking allocation sizes

[jb at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65921

--- Comment #2 from Janne Blomqvist <jb at gcc dot gnu.org> ---
libgfortran/runtime/memory.c (xmallocarray) has been fixed for GCC 10, frontend
part still todo.