Aliased rb_ary_new_from_args to rb_ary_new3.

In MRI it's the other way around: rb_ary_new3 is the alias. However, in our case
this breaks certain parts (e.g. rubysl-openssl) for reasons unknown to me. Since
it doesn't really matter which one is the alias I decided to alias
rb_ary_new_from_args to rb_ary_new3 instead of the other way around.
Added specs for rb_ary_new_from_args.