vec.h (class vec_prefix): Change into struct.

	* vec.h (class vec_prefix): Change into struct.
	Rename field alloc_PRIVATE_ back to alloc_.
	Rename field num_PRIVATE_ to num_.
	Update all users.
	(class vec<T, A, vl_embed>): Rename field pfx_PRIVATE_ to vecpfx_.
	Rename field data_PRIVATE_ to vecdata_.
	Update all users.
	(class vec<T, A, vl_ptr>): Make every field public.
	Rename field vec_PRIVATE_ back to vec_.
	Update all users.

From-SVN: r193675