Changes to make the simulator work again.

Changes to make the simulator work again.
	* callback.c (fdbad): Fix typo in comment.
	(os_close, os_isatty, os_lseek, os_read, os_write): Use if statements
	rather than || to get correct return value.
	(os_write_stdout): Pass missing first argument to os_write.
	* remote-sim.c: Include callback.h.
	(_initialize_remote_sim): Call sim_set_callbacks and then initialize
	the callbacks.