The (sole) use of memcpy in our public header is now replaced to
directly call ruby_nonempty_memcpy, and the previous definition of
memcpy is now internal-only. [Bug#18893]
The count of rb_alloc_tmp_buffer_with_count is the allocation size
counted in VALUE size but not in the requested element size.
Co-authored-by: Yusuke Endoh <mame@ruby-lang.org>
Co-authored-by: Koichi Sasada <ko1@atdot.net>
Now that RUBY_ALIGNOF behaves like C11's _Alignof. This is not
necessarily the best stack arrangement. We can just give up using
__builtin_alloca_with_align(), and let alloca choose what is optimal.
