Share vtables instead of replicating them for each unit.

Share vtables instead of replicating them for each unit.

2012-03-16  Janne Blomqvist  <jb@gcc.gnu.org>

	* io/unix.h (struct stream): Rename to stream_vtable.
	(struct stream): New struct definition.
	(sread): Dereference vtable pointer.
	(swrite): Likewise.
	(sseek): Likewise.
	(struncate): Likewise.
	(sflush): Likewise.
	(sclose): Likewise.
	* io/unix.c (raw_vtable): New variable.
	(buf_vtable): Likewise.
	(mem_vtable): Likewise.
	(mem4_vtable): Likewise.
	(raw_init): Assign vtable pointer.
	(buf_init): Likewise.
	(open_internal): Likewise.
	(open_internal4): Likewise.

From-SVN: r185454