* array.c (ary_memfill): added.
* array.c (rb_ary_initialize): use ary_memfill().
* array.c (rb_ary_fill): ditto.
* array.c (rb_ary_slice_bang): use RARRAY_RAWPTR() because
  this code creates no new references.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42105 b2dd03c8-39d4-4d8f-98ff-823fe69b080e