Don't emit diagnostics. Let callers do that.

Don't emit diagnostics.  Let callers do that.

Don't include "error.h".
(save_cwd): Don't call error.  Ensure that errno is valid
when returning nonzero.

(restore_cwd): Remove two parameters.
Simplify.  Don't call error upon failure.  Let callers do that.
(save_cwd): Mention that Irix 5.3 has the same problem as SunOS4
when auditing is enabled.  But don't bother updating the #if.